<SUBMISSION>
<ACCESSION-NUMBER>0000912057-01-524580
<TYPE>S-8
<PUBLIC-DOCUMENT-COUNT>3
<FILING-DATE>20010720
<EFFECTIVENESS-DATE>20010720
<FILER>
<COMPANY-DATA>
<CONFORMED-NAME>AEROGEN INC
<CIK>0001039160
<ASSIGNED-SIC>3841
<IRS-NUMBER>330488580
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>1231
</COMPANY-DATA>
<FILING-VALUES>
<FORM-TYPE>S-8
<ACT>33
<FILE-NUMBER>333-65518
<FILM-NUMBER>1685219
</FILING-VALUES>
<BUSINESS-ADDRESS>
<STREET1>1310 CORONADO DR
<CITY>SANTA CLARA
<STATE>CA
<ZIP>95054
<PHONE>4085432400
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>1310 ORLEANS DRIVE
<CITY>SUNNYVALE
<STATE>CA
<ZIP>94089
</MAIL-ADDRESS>
</FILER>
<DOCUMENT>
<TYPE>S-8
<SEQUENCE>1
<FILENAME>a2054743zs-8.htm
<DESCRIPTION>S-8
<TEXT>

<HTML>
<HEAD>
<TITLE> Prepared by MERRILL CORPORATION
</TITLE>
</HEAD>
<BODY BGCOLOR="#FFFFFF" LINK=BLUE  VLINK=PURPLE>
<BR>
<FONT SIZE=3 ><A HREF="#01PAL2138_1">QuickLinks</A></FONT>
<font size=3> -- Click here to rapidly navigate through this document</font>
<P ALIGN="CENTER"><FONT SIZE=2><B>As filed with the Securities and Exchange Commission on July&nbsp;20, 2001 Registration  </B></FONT></P>

<P ALIGN="RIGHT"><FONT SIZE=2><B> No.&nbsp;333-&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </B></FONT></P>

<HR NOSHADE>
<HR NOSHADE>
<P ALIGN="CENTER"><FONT SIZE=5><B>SECURITIES AND EXCHANGE COMMISSION<BR>  </B></FONT><FONT SIZE=2><B>Washington, D.C. 20549  </B></FONT></P>

<HR NOSHADE ALIGN="CENTER" WIDTH="120">
<P ALIGN="CENTER"><FONT SIZE=5><B>FORM S-8<BR>  </B></FONT><FONT SIZE=2><B>REGISTRATION STATEMENT<BR>
UNDER<BR>
THE SECURITIES ACT OF 1933  </B></FONT></P>

<HR NOSHADE ALIGN="CENTER" WIDTH="120">
<P ALIGN="CENTER"><FONT SIZE=5><B>AEROGEN,&nbsp;INC.<BR>  </B></FONT><FONT SIZE=2>(Exact name of registrant as specified in its charter) </FONT></P>

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<TD WIDTH="31%" ALIGN="CENTER"><FONT SIZE=2><B>Delaware</B></FONT><FONT SIZE=2><BR>
(State of Incorporation)</FONT></TD>
<TD WIDTH="22%"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD WIDTH="47%" ALIGN="CENTER"><FONT SIZE=2><B>33-0488580<BR> </B></FONT><FONT SIZE=2>(I.R.S. Employer Identification No.)</FONT></TD>
</TR>
</TABLE></DIV>
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<HR NOSHADE ALIGN="CENTER" WIDTH="120">
<P ALIGN="CENTER"><FONT SIZE=2><B>1310 Orleans Drive<BR>
Sunnyvale, CA 94089<BR>  </B></FONT><FONT SIZE=2>(Address of principal executive offices) </FONT></P>

<HR NOSHADE ALIGN="CENTER" WIDTH="120">
<P ALIGN="CENTER"><FONT SIZE=2><B>2000 Equity Incentive Plan<BR>
2000 Employee Stock Purchase Plan<BR>  </B></FONT><FONT SIZE=2>(Full title of the plans) </FONT></P>

<P ALIGN="CENTER"><FONT SIZE=2><B>Carol A. Gamble<BR>
Vice President and General Counsel<BR>
AeroGen,&nbsp;Inc.<BR>
1310 Orleans Drive<BR>
Sunnyvale, CA 94089<BR>
(408)&nbsp;543-2400<BR>  </B></FONT><FONT SIZE=2>(Name, address, including zip code, and telephone number, including area code, of agent for service) </FONT></P>

<HR NOSHADE ALIGN="CENTER" WIDTH="120">
<P ALIGN="CENTER"><FONT SIZE=2>Copies
to:<BR></FONT> <FONT SIZE=2><B>Robert J. Brigham<BR>
Cooley Godward LLP<BR>
Five Palo Alto Square<BR>
3000 El Camino Real<BR>
Palo Alto, CA 94306<BR>
(650)&nbsp;843-5000  </B></FONT></P>

<HR NOSHADE ALIGN="CENTER" WIDTH="120">
<P ALIGN="CENTER"><FONT SIZE=2><B> CALCULATION OF REGISTRATION FEE  </B></FONT></P>

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<TABLE WIDTH="94%" BORDER=0 CELLSPACING=0 CELLPADDING=0>
<TR VALIGN="TOP">
<TD COLSPAN=9><HR NOSHADE></TD>
</TR>
<TR VALIGN="BOTTOM">
<TH WIDTH="30%" ALIGN="CENTER"><FONT SIZE=1><B>Title of Securities<BR>
to be Registered</B></FONT><BR></TH>
<TH WIDTH="1%"><FONT SIZE=1>&nbsp;</FONT></TH>
<TH WIDTH="17%" ALIGN="CENTER"><FONT SIZE=1><B>Amount to be Registered</B></FONT><BR></TH>
<TH WIDTH="1%"><FONT SIZE=1>&nbsp;</FONT></TH>
<TH WIDTH="17%" ALIGN="CENTER"><FONT SIZE=1><B>Proposed<BR>
Offering<BR>
Price per Share (1)</B></FONT><BR></TH>
<TH WIDTH="1%"><FONT SIZE=1>&nbsp;</FONT></TH>
<TH WIDTH="17%" ALIGN="CENTER"><FONT SIZE=1><B>Proposed Maximum<BR>
Aggregate<BR>
Offering Price (1)</B></FONT><BR></TH>
<TH WIDTH="1%"><FONT SIZE=1>&nbsp;</FONT></TH>
<TH WIDTH="15%" ALIGN="CENTER"><FONT SIZE=1><B>Amount of<BR>
Registration Fee</B></FONT><BR></TH>
</TR>
<TR VALIGN="TOP">
<TD COLSPAN=9><HR NOSHADE></TD>
</TR>
<TR BGCOLOR="#CCEEFF" VALIGN="BOTTOM">
<TD WIDTH="30%"><FONT SIZE=2>Stock Options and Common Stock (par value $.001)</FONT></TD>
<TD WIDTH="1%"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD WIDTH="17%" ALIGN="CENTER"><FONT SIZE=2>1,126,876 shares</FONT></TD>
<TD WIDTH="1%"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD WIDTH="17%" ALIGN="CENTER"><FONT SIZE=2>$4.57</FONT></TD>
<TD WIDTH="1%"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD WIDTH="17%" ALIGN="CENTER"><FONT SIZE=2>$5,149,824</FONT></TD>
<TD WIDTH="1%"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD WIDTH="15%" ALIGN="CENTER"><FONT SIZE=2>$1,288</FONT></TD>
</TR>
<TR VALIGN="TOP">
<TD COLSPAN=9><HR NOSHADE></TD>
</TR>
</TABLE>
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<DL compact>
<DT><FONT SIZE=2>(1)</FONT></DT><DD><FONT SIZE=2>Estimated
solely for the purpose of calculating the amount of the registration fee pursuant to Rule&nbsp;457(h). The price per share and aggregate offering price are based upon
the average of the high and low prices of Registrant's Common Stock on July&nbsp;19, 2001 as reported on the Nasdaq National Market. </FONT></DD></DL>
<BR>
<HR NOSHADE>
<HR NOSHADE>
<HR NOSHADE>
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<P><FONT SIZE=2>
&nbsp;&nbsp;&nbsp;&nbsp;The chart below details the calculations of the registration fee: </FONT></P>

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<TABLE WIDTH="94%" BORDER=0 CELLSPACING=0 CELLPADDING=0>
<TR VALIGN="BOTTOM">
<TH WIDTH="44%" ALIGN="CENTER"><FONT SIZE=1><B>Securities</B></FONT><HR NOSHADE></TH>
<TH WIDTH="2%"><FONT SIZE=1>&nbsp;</FONT></TH>
<TH WIDTH="12%" ALIGN="CENTER"><FONT SIZE=1><B>Number of Shares</B></FONT><HR NOSHADE></TH>
<TH WIDTH="2%"><FONT SIZE=1>&nbsp;</FONT></TH>
<TH COLSPAN=2 ALIGN="CENTER"><FONT SIZE=1><B>Proposed Offering<BR>
Price Per Share</B></FONT><HR NOSHADE></TH>
<TH WIDTH="2%"><FONT SIZE=1>&nbsp;</FONT></TH>
<TH COLSPAN=2 ALIGN="CENTER"><FONT SIZE=1><B>Proposed<BR>
Maximum<BR>
Aggregate Offering<BR>
Price</B></FONT><HR NOSHADE></TH>
</TR>
<TR BGCOLOR="#CCEEFF" VALIGN="BOTTOM">
<TD WIDTH="44%"><FONT SIZE=2>Shares issuable pursuant to the 2000 Equity Incentive Plan</FONT></TD>
<TD WIDTH="2%"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD WIDTH="12%" ALIGN="RIGHT"><FONT SIZE=2>921,989</FONT></TD>
<TD WIDTH="2%"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD WIDTH="2%"><FONT SIZE=2>$</FONT></TD>
<TD WIDTH="16%" ALIGN="RIGHT"><FONT SIZE=2>4.57</FONT></TD>
<TD WIDTH="2%"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD WIDTH="2%"><FONT SIZE=2>$</FONT></TD>
<TD WIDTH="17%" ALIGN="RIGHT"><FONT SIZE=2>4,213,490</FONT></TD>
</TR>
<TR BGCOLOR="White" VALIGN="BOTTOM">
<TD WIDTH="44%"><FONT SIZE=2>Shares issuable pursuant to the 2000 Employee Stock Purchase Plan</FONT></TD>
<TD WIDTH="2%"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD WIDTH="12%" ALIGN="RIGHT"><FONT SIZE=2>204,887</FONT></TD>
<TD WIDTH="2%"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD WIDTH="2%"><FONT SIZE=2>$</FONT></TD>
<TD WIDTH="16%" ALIGN="RIGHT"><FONT SIZE=2>4.57</FONT></TD>
<TD WIDTH="2%"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD WIDTH="2%"><FONT SIZE=2>$</FONT></TD>
<TD WIDTH="17%" ALIGN="RIGHT"><FONT SIZE=2>936,334</FONT></TD>
</TR>
<TR BGCOLOR="#CCEEFF" VALIGN="BOTTOM">
<TD WIDTH="44%"><FONT SIZE=2>Proposed Maximum Offering Price</FONT></TD>
<TD WIDTH="2%"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD WIDTH="12%" ALIGN="RIGHT"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD WIDTH="2%"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD WIDTH="2%"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD WIDTH="16%" ALIGN="RIGHT"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD WIDTH="2%"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD WIDTH="2%"><FONT SIZE=2>$</FONT></TD>
<TD WIDTH="17%" ALIGN="RIGHT"><FONT SIZE=2>5,149,824</FONT></TD>
</TR>
<TR BGCOLOR="White" VALIGN="BOTTOM">
<TD WIDTH="44%"><FONT SIZE=2>Registration Fee</FONT></TD>
<TD WIDTH="2%"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD WIDTH="12%" ALIGN="RIGHT"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD WIDTH="2%"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD WIDTH="2%"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD WIDTH="16%" ALIGN="RIGHT"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD WIDTH="2%"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD WIDTH="2%"><FONT SIZE=2>$</FONT></TD>
<TD WIDTH="17%" ALIGN="RIGHT"><FONT SIZE=2>1,288</FONT></TD>
</TR>
</TABLE>
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<P ALIGN="CENTER"><FONT SIZE=2><A
NAME="dc2138_incorporation_by_reference_of___inc03053"> </A>
<A NAME="toc_dc2138_1"> </A>
<BR></FONT><FONT SIZE=2><B>INCORPORATION BY REFERENCE OF CONTENTS OF<BR>  REGISTRATION STATEMENT ON FORM S-8 NO. 333-50038    <BR>  </B></FONT></P>

<P><FONT SIZE=2>&nbsp;&nbsp;&nbsp;&nbsp;The contents of Registration Statement on Form&nbsp;S-8 No.&nbsp;333-50038 filed with the Securities and Exchange Commission on
November&nbsp;16, 2000 are incorporated by reference herein. </FONT></P>

<P ALIGN="CENTER"><FONT SIZE=2><A
NAME="dc2138_interests_of_named_experts_and_counsel"> </A>
<A NAME="toc_dc2138_2"> </A>
<BR></FONT><FONT SIZE=2><B>INTERESTS OF NAMED EXPERTS AND COUNSEL    <BR>  </B></FONT></P>

<P><FONT SIZE=2>&nbsp;&nbsp;&nbsp;&nbsp;</FONT><FONT SIZE=2><B>Carol A. Gamble, Vice President and General Counsel of the Company, has provided the Company an opinion as to the validity of the
Common Stock offered hereby. Ms.&nbsp;Gamble has options to purchase 150,000 shares of the Company Common Stock.</B></FONT></P>

<P ALIGN="CENTER"><FONT SIZE=2><A
NAME="dc2138_exhibits"> </A>
<A NAME="toc_dc2138_3"> </A>
<BR></FONT><FONT SIZE=2><B>EXHIBITS    <BR>  </B></FONT></P>

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<TR VALIGN="BOTTOM">
<TH WIDTH="10%" ALIGN="CENTER"><FONT SIZE=1><B>Exhibit<BR>
Number</B></FONT><HR NOSHADE></TH>
<TH WIDTH="3%"><FONT SIZE=1>&nbsp;</FONT></TH>
<TH WIDTH="88%" ALIGN="LEFT"><FONT SIZE=1>&nbsp;</FONT><BR></TH>
</TR>
<TR VALIGN="TOP">
<TD WIDTH="10%"><FONT SIZE=2>&nbsp;5.1</FONT></TD>
<TD WIDTH="3%"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD WIDTH="88%"><FONT SIZE=2>Opinion of Counsel.</FONT></TD>
</TR>
<TR VALIGN="TOP">
<TD WIDTH="10%"><FONT SIZE=2><BR>
23.1</FONT></TD>
<TD WIDTH="3%"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="88%"><FONT SIZE=2><BR>
Consent of Independent Accountants.</FONT></TD>
</TR>
<TR VALIGN="TOP">
<TD WIDTH="10%"><FONT SIZE=2><BR>
23.2</FONT></TD>
<TD WIDTH="3%"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="88%"><FONT SIZE=2><BR>
Consent of Counsel is contained in Exhibit 5.1 to this Registration Statement.</FONT></TD>
</TR>
<TR VALIGN="TOP">
<TD WIDTH="10%"><FONT SIZE=2><BR>
24.1</FONT></TD>
<TD WIDTH="3%"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="88%"><FONT SIZE=2><BR>
Power of Attorney is contained on the signature pages.</FONT></TD>
</TR>
<TR VALIGN="TOP">
<TD WIDTH="10%"><FONT SIZE=2><BR>
99.1*</FONT></TD>
<TD WIDTH="3%"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="88%"><FONT SIZE=2><BR>
2000 Equity Incentive Plan and related documents.</FONT></TD>
</TR>
<TR VALIGN="TOP">
<TD WIDTH="10%"><FONT SIZE=2><BR>
99.2*</FONT></TD>
<TD WIDTH="3%"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="88%"><FONT SIZE=2><BR>
2000 Employee Stock Purchase Plan and related documents.</FONT></TD>
</TR>
</TABLE>
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<DL compact>
<DT><FONT SIZE=2>*</FONT></DT><DD><FONT SIZE=2>Documents
incorporated by reference from the Company's Registration Statement on Form&nbsp;S-1, as amended (No.&nbsp;333-44470), originally filed with the
Securities and Exchange Commission on August&nbsp;25, 2000 </FONT></DD></DL>
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<P ALIGN="CENTER"><FONT SIZE=2><A
NAME="de2138_signatures"> </A>
<A NAME="toc_de2138_1"> </A>
<BR></FONT><FONT SIZE=2><B>SIGNATURES    <BR>  </B></FONT></P>

<P><FONT SIZE=2>&nbsp;&nbsp;&nbsp;&nbsp;Pursuant to the requirements of the Securities Act of 1933, as amended, the Registrant certifies that it has reasonable grounds to believe that it meets all of
the requirements for filing on Form&nbsp;S-8 and has duly caused this Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of
Sunnyvale, State of California, on July&nbsp;20, 2001. </FONT></P>

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<TR VALIGN="TOP">
<TD WIDTH="47%"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD WIDTH="3%"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD COLSPAN=2><FONT SIZE=2>AEROGEN,&nbsp;INC.</FONT></TD>
</TR>
<TR VALIGN="TOP">
<TD WIDTH="47%"><FONT SIZE=2><BR>
&nbsp;</FONT></TD>
<TD WIDTH="3%"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="4%"><BR><FONT SIZE=2>By:</FONT></TD>
<TD WIDTH="46%"><FONT SIZE=2><BR>
/s/&nbsp;</FONT><FONT SIZE=2>JANE E. SHAW</FONT><FONT SIZE=2>&nbsp;&nbsp;&nbsp;</FONT><HR NOSHADE><FONT SIZE=2> Jane E. Shaw<BR>
Chairman and Chief Executive Officer<BR>
(Principal Executive Officer)</FONT></TD>
</TR>
</TABLE>
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<P ALIGN="CENTER"><FONT SIZE=2><A
NAME="de2138_power_of_attorney"> </A>
<A NAME="toc_de2138_2"> </A>
<BR></FONT><FONT SIZE=2><B>POWER OF ATTORNEY    <BR>  </B></FONT></P>

<P><FONT SIZE=2>&nbsp;&nbsp;&nbsp;&nbsp;</FONT><FONT SIZE=2><B>KNOW ALL PERSONS BY THESE PRESENTS</B></FONT><FONT SIZE=2>, that each person whose signature appears below constitutes and appoints
Carol A. Gamble and Deborah K. Karlson and each or any one of them, his true and lawful attorney-in-fact and agent, with full power of substitution and resubstitution, for him
and in his name, place and stead, in any and all capacities, to sign any and all amendments (including post-effective amendments) to this Registration Statement, and to file the same, with
all exhibits thereto, and other documents in connection therewith, with the Securities and Exchange Commission, granting unto said attorneys-in-fact and agents, and each of
them, full power and authority to do and perform each and every act and thing requisite and necessary to be done in connection therewith, as fully to all intents and purposes as he might or could do
in person, hereby ratifying and confirming all that said attorneys-in-fact and agents, or any of them, or their or his substitutes or substitute, may lawfully do or cause to be
done by virtue hereof. </FONT></P>

<P><FONT SIZE=2>&nbsp;&nbsp;&nbsp;&nbsp;Pursuant
to the requirements of the Securities Act of 1933, this Registration Statement has been signed by the following persons in the capacities and on the dates indicated. </FONT></P>

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<TH WIDTH="47%" ALIGN="CENTER"><FONT SIZE=1><B>Signature</B></FONT><HR NOSHADE></TH>
<TH WIDTH="3%"><FONT SIZE=1>&nbsp;</FONT></TH>
<TH WIDTH="29%" ALIGN="CENTER"><FONT SIZE=1><B>Title</B></FONT><HR NOSHADE></TH>
<TH WIDTH="3%"><FONT SIZE=1>&nbsp;</FONT></TH>
<TH WIDTH="19%" ALIGN="CENTER"><FONT SIZE=1><B>Date</B></FONT><HR NOSHADE></TH>
</TR>
<TR VALIGN="BOTTOM">
<TD WIDTH="47%" ALIGN="CENTER" VALIGN="CENTER"><BR><FONT SIZE=2>&nbsp;</FONT></TD>
<TD WIDTH="3%" VALIGN="CENTER"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="29%" VALIGN="CENTER"><FONT SIZE=2><BR>
&nbsp;</FONT></TD>
<TD WIDTH="3%" VALIGN="CENTER"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="19%" VALIGN="CENTER"><FONT SIZE=2><BR>
&nbsp;</FONT></TD>
</TR>
<TR VALIGN="TOP">
<TD WIDTH="47%" ALIGN="CENTER" VALIGN="CENTER"><FONT SIZE=2>/s/&nbsp;</FONT><FONT SIZE=2>JANE E. SHAW</FONT><FONT SIZE=2>&nbsp;&nbsp;&nbsp;</FONT><HR NOSHADE><FONT SIZE=2><B>JANE E. SHAW</B></FONT></TD>
<TD WIDTH="3%" VALIGN="CENTER"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD WIDTH="29%" VALIGN="CENTER"><FONT SIZE=2>Chairman, Chief Executive Officer and Director<BR>
(Principal Executive Officer)</FONT></TD>
<TD WIDTH="3%" VALIGN="CENTER"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD WIDTH="19%" ALIGN="CENTER" VALIGN="CENTER"><FONT SIZE=2>July 20, 2001</FONT></TD>
</TR>
<TR VALIGN="TOP">
<TD WIDTH="47%" ALIGN="CENTER" VALIGN="CENTER"><FONT SIZE=2><BR>
/s/&nbsp;</FONT><FONT SIZE=2>DEBORAH K. KARLSON</FONT><FONT SIZE=2>&nbsp;&nbsp;&nbsp;</FONT><HR NOSHADE><FONT SIZE=2><B>DEBORAH K. KARLSON</B></FONT></TD>
<TD WIDTH="3%" VALIGN="CENTER"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="29%" VALIGN="CENTER"><FONT SIZE=2><BR>
Chief Financial Officer (Principal Financial and Accounting Officer)</FONT></TD>
<TD WIDTH="3%" VALIGN="CENTER"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="19%" ALIGN="CENTER" VALIGN="CENTER"><FONT SIZE=2><BR>
July 20, 2001</FONT></TD>
</TR>
<TR VALIGN="BOTTOM">
<TD WIDTH="47%" ALIGN="CENTER" VALIGN="CENTER"><FONT SIZE=2><BR>
/s/&nbsp;</FONT><FONT SIZE=2>THOMAS R. BARUCH</FONT><FONT SIZE=2>&nbsp;&nbsp;&nbsp;</FONT><HR NOSHADE><FONT SIZE=2><B>THOMAS R. BARUCH</B></FONT></TD>
<TD WIDTH="3%" VALIGN="CENTER"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="29%" VALIGN="CENTER"><FONT SIZE=2><BR>
Director</FONT></TD>
<TD WIDTH="3%" VALIGN="CENTER"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="19%" ALIGN="CENTER" VALIGN="CENTER"><FONT SIZE=2><BR>
July 20, 2001</FONT></TD>
</TR>
<TR VALIGN="BOTTOM">
<TD WIDTH="47%" ALIGN="CENTER" VALIGN="CENTER"><FONT SIZE=2><BR>
/s/&nbsp;</FONT><FONT SIZE=2>JEAN-JACQUES BIENAIM&Eacute;</FONT><FONT SIZE=2>&nbsp;&nbsp;&nbsp;</FONT><HR NOSHADE><FONT SIZE=2><B>JEAN-JACQUES BIENAIM&Eacute;</B></FONT></TD>
<TD WIDTH="3%" VALIGN="CENTER"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="29%" VALIGN="CENTER"><FONT SIZE=2><BR>
Director</FONT></TD>
<TD WIDTH="3%" VALIGN="CENTER"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="19%" ALIGN="CENTER" VALIGN="CENTER"><FONT SIZE=2><BR>
July 20, 2001</FONT></TD>
</TR>
<TR VALIGN="BOTTOM">
<TD WIDTH="47%" ALIGN="CENTER" VALIGN="CENTER"><FONT SIZE=2><BR>
/s/&nbsp;</FONT><FONT SIZE=2>PHYLLIS I. GARDNER</FONT><FONT SIZE=2>&nbsp;&nbsp;&nbsp;</FONT><HR NOSHADE><FONT SIZE=2><B>PHYLLIS I. GARDNER</B></FONT></TD>
<TD WIDTH="3%" VALIGN="CENTER"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="29%" VALIGN="CENTER"><FONT SIZE=2><BR>
Director</FONT></TD>
<TD WIDTH="3%" VALIGN="CENTER"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="19%" ALIGN="CENTER" VALIGN="CENTER"><FONT SIZE=2><BR>
July 20, 2001</FONT></TD>
</TR>
</TABLE>
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<TD WIDTH="47%" ALIGN="CENTER" VALIGN="CENTER"><FONT SIZE=2><BR>
/s/&nbsp;</FONT><FONT SIZE=2>SUSAN D. DESMOND-HELLMANN</FONT><FONT SIZE=2>&nbsp;&nbsp;&nbsp;</FONT><HR NOSHADE><FONT SIZE=2><B>SUSAN D. DESMOND-HELLMANN</B></FONT></TD>
<TD WIDTH="3%" VALIGN="CENTER"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="29%" VALIGN="CENTER"><FONT SIZE=2><BR>
Director</FONT></TD>
<TD WIDTH="3%" VALIGN="CENTER"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="19%" ALIGN="CENTER" VALIGN="CENTER"><FONT SIZE=2><BR>
July 20, 2001</FONT></TD>
</TR>
<TR VALIGN="BOTTOM">
<TD WIDTH="47%" ALIGN="CENTER" VALIGN="CENTER"><FONT SIZE=2><BR>
/s/&nbsp;</FONT><FONT SIZE=2>YEHUDA IVRI</FONT><FONT SIZE=2>&nbsp;&nbsp;&nbsp;</FONT><HR NOSHADE><FONT SIZE=2><B>YEHUDA IVRI</B></FONT></TD>
<TD WIDTH="3%" VALIGN="CENTER"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="29%" VALIGN="CENTER"><FONT SIZE=2><BR>
Director</FONT></TD>
<TD WIDTH="3%" VALIGN="CENTER"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="19%" ALIGN="CENTER" VALIGN="CENTER"><FONT SIZE=2><BR>
July 20, 2001</FONT></TD>
</TR>
<TR VALIGN="BOTTOM">
<TD WIDTH="47%" ALIGN="CENTER" VALIGN="CENTER"><FONT SIZE=2><BR>
/s/&nbsp;</FONT><FONT SIZE=2>PHILIP M. YOUNG</FONT><FONT SIZE=2>&nbsp;&nbsp;&nbsp;</FONT><HR NOSHADE><FONT SIZE=2><B>PHILIP M. YOUNG</B></FONT></TD>
<TD WIDTH="3%" VALIGN="CENTER"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="29%" VALIGN="CENTER"><FONT SIZE=2><BR>
Director</FONT></TD>
<TD WIDTH="3%" VALIGN="CENTER"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="19%" ALIGN="CENTER" VALIGN="CENTER"><FONT SIZE=2><BR>
July 20, 2001</FONT></TD>
</TR>
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<P ALIGN="CENTER"><FONT SIZE=2><A
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<BR></FONT><FONT SIZE=2><B>EXHIBIT INDEX    <BR>  </B></FONT></P>

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<TH WIDTH="10%" ALIGN="CENTER"><FONT SIZE=1><B>Exhibit<BR>
Number</B></FONT><HR NOSHADE></TH>
<TH WIDTH="3%"><FONT SIZE=1>&nbsp;</FONT></TH>
<TH WIDTH="88%" ALIGN="LEFT"><FONT SIZE=1><B>Description<BR> </B></FONT><HR NOSHADE></TH>
</TR>
<TR VALIGN="TOP">
<TD WIDTH="10%"><FONT SIZE=2>&nbsp;5.1</FONT></TD>
<TD WIDTH="3%"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD WIDTH="88%"><FONT SIZE=2>Opinion of Counsel.</FONT></TD>
</TR>
<TR VALIGN="TOP">
<TD WIDTH="10%"><FONT SIZE=2><BR>
23.1</FONT></TD>
<TD WIDTH="3%"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="88%"><FONT SIZE=2><BR>
Consent of Independent Accountants.</FONT></TD>
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<TD WIDTH="10%"><FONT SIZE=2><BR>
23.2</FONT></TD>
<TD WIDTH="3%"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="88%"><FONT SIZE=2><BR>
Consent of Counsel is contained in Exhibit 5.1 to this Registration Statement.</FONT></TD>
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<TR VALIGN="TOP">
<TD WIDTH="10%"><FONT SIZE=2><BR>
24.1</FONT></TD>
<TD WIDTH="3%"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="88%"><FONT SIZE=2><BR>
Power of Attorney is contained on the signature pages.</FONT></TD>
</TR>
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<TD WIDTH="10%"><FONT SIZE=2><BR>
99.1</FONT></TD>
<TD WIDTH="3%"><FONT SIZE=2><BR>*</FONT></TD>
<TD WIDTH="88%"><FONT SIZE=2><BR>
2000 Equity Incentive Plan and related documents.</FONT></TD>
</TR>
<TR VALIGN="TOP">
<TD WIDTH="10%"><FONT SIZE=2><BR>
99.2</FONT></TD>
<TD WIDTH="3%"><FONT SIZE=2><BR>*</FONT></TD>
<TD WIDTH="88%"><FONT SIZE=2><BR>
2000 Employee Stock Purchase Plan and related documents.</FONT></TD>
</TR>
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<HR NOSHADE ALIGN="LEFT" WIDTH="120">
<DL compact>
<DT><FONT SIZE=2>*</FONT></DT><DD><FONT SIZE=2>Documents
incorporated by reference from the Company's Registration Statement on Form&nbsp;S-1, as amended (No.&nbsp;333-44470), filed with the Securities
and Exchange Commission on August&nbsp;25, 2000. </FONT></DD></DL>
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<FONT SIZE=2><A HREF="#toc_dc2138_1">INCORPORATION BY REFERENCE OF CONTENTS OF REGISTRATION STATEMENT ON FORM S-8 NO. 333-50038</A></FONT><BR>
<FONT SIZE=2><A HREF="#toc_dc2138_2">INTERESTS OF NAMED EXPERTS AND COUNSEL</A></FONT><BR>
<FONT SIZE=2><A HREF="#toc_dc2138_3">EXHIBITS</A></FONT><BR>
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<FONT SIZE=2><A HREF="#toc_de2138_1">SIGNATURES</A></FONT><BR>
<FONT SIZE=2><A HREF="#toc_de2138_2">POWER OF ATTORNEY</A></FONT><BR>
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<FONT SIZE=2><A HREF="#toc_dg2138_1">EXHIBIT INDEX</A></FONT><BR>
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<DOCUMENT>
<TYPE>EX-5.1
<SEQUENCE>2
<FILENAME>a2054743zex-5_1.htm
<DESCRIPTION>EX 5.1
<TEXT>

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<P ALIGN="RIGHT"><FONT SIZE=2><A
NAME="dk2138_exhibit_5.1"> </A>
<A NAME="toc_dk2138_1"> </A>
<BR></FONT><FONT SIZE=2><B>EXHIBIT 5.1    <BR>  </B></FONT></P>

<P><FONT SIZE=2>July&nbsp;20,
2001 </FONT></P>

<P><FONT SIZE=2>Aerogen,&nbsp;Inc.<BR>
1310 Orleans Drive<BR>
Sunnyvale, CA 94089 </FONT></P>

<P><FONT SIZE=2>Ladies
and Gentlemen: </FONT></P>

<P><FONT SIZE=2>&nbsp;&nbsp;&nbsp;&nbsp;You
have requested my opinion with respect to certain matters in connection with the filing by Aerogen,&nbsp;Inc. (the "Company") of a Registration Statement on
Form&nbsp;S-8 (the "Registration Statement") with the Securities and Exchange Commission covering the offering of up to 1,126,876 shares of the Company's Common Stock, $.001 par value,
(the "Shares") pursuant to its 2000 Equity Incentive Plan and 2000 Employee Stock Purchase Plan (together, the "Plans"). </FONT></P>

<P><FONT SIZE=2>&nbsp;&nbsp;&nbsp;&nbsp;In
connection with this opinion, I have examined the Registration Statement and related Prospectus, your Certificate of Incorporation and By-laws, as amended, and such
other documents, records, certificates, memoranda and other instruments as I deem necessary as a basis for this opinion. I have assumed the genuineness and authenticity of all documents submitted to
me as originals, the conformity to originals of all documents submitted to me as copies thereof, and the due execution and delivery of all documents where due execution and delivery are a prerequisite
to the effectiveness thereof. </FONT></P>

<P><FONT SIZE=2>&nbsp;&nbsp;&nbsp;&nbsp;On
the basis of the foregoing, and in reliance thereon, I am of the opinion that the Shares, when sold and issued in accordance with the Plans, the Registration Statement and related
Prospectus, will be validly issued, fully paid, and nonassessable (except as to shares issued pursuant to certain deferred payment arrangements, which will be fully paid and nonassessable when such
deferred payments are made in full). </FONT></P>

<P><FONT SIZE=2>&nbsp;&nbsp;&nbsp;&nbsp;I
consent to the filing of this opinion as an exhibit to the Registration Statement. </FONT></P>

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<TD WIDTH="47%"><FONT SIZE=2>Very truly yours,</FONT></TD>
<TD WIDTH="53%"><FONT SIZE=2>&nbsp;</FONT></TD>
</TR>
<TR VALIGN="BOTTOM">
<TD WIDTH="47%"><FONT SIZE=2><BR>
/s/&nbsp;</FONT><FONT SIZE=2>CAROL A. GAMBLE</FONT><FONT SIZE=2>&nbsp;&nbsp;&nbsp;</FONT><HR NOSHADE><FONT SIZE=2> Carol A. Gamble<BR>
Vice President and General Counsel</FONT></TD>
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&nbsp;</FONT></TD>
</TR>
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<TYPE>EX-23.1
<SEQUENCE>3
<FILENAME>a2054743zex-23_1.htm
<DESCRIPTION>EX 23.1
<TEXT>

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<BR></FONT><FONT SIZE=2><B>EXHIBIT 23.1    <BR>  </B></FONT></P>

<P ALIGN="CENTER"><FONT SIZE=2><A
NAME="dm2138_consent_of_independent_accountants"> </A>
<A NAME="toc_dm2138_2"> </A>
<BR></FONT><FONT SIZE=2><B>CONSENT OF INDEPENDENT ACCOUNTANTS    <BR>  </B></FONT></P>

<P><FONT SIZE=2>&nbsp;&nbsp;&nbsp;&nbsp;We hereby consent to the incorporation by reference in this Registration Statement on Form&nbsp;S-8 of our report dated February&nbsp;9, 2001,
relating to the consolidated financial statements which appear in AeroGen,&nbsp;Inc.'s Annual Report on Form&nbsp;10-K for the year ended December&nbsp;31, 2000. </FONT></P>

<UL>
<UL>
<UL>
<UL>
<UL>
<UL>
<UL>
<UL>
<UL>
<UL>
<UL>

<P><FONT SIZE=2>/s/
PricewaterhouseCoopers LLP </FONT></P>

</UL>
</UL>
</UL>
</UL>
</UL>
</UL>
</UL>
</UL>
</UL>
</UL>
</UL>

<P><FONT SIZE=2>San
Jose, California<BR>
July&nbsp;20, 2001 </FONT></P>

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<FONT SIZE=2><A HREF="#toc_dm2138_2">CONSENT OF INDEPENDENT ACCOUNTANTS</A></FONT><BR>
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