<SUBMISSION>
<ACCESSION-NUMBER>0000950123-04-005343
<TYPE>424B3
<PUBLIC-DOCUMENT-COUNT>1
<FILING-DATE>20040429
<FILER>
<COMPANY-DATA>
<CONFORMED-NAME>REGENERON PHARMACEUTICALS INC
<CIK>0000872589
<ASSIGNED-SIC>2834
<IRS-NUMBER>133444607
<STATE-OF-INCORPORATION>NY
<FISCAL-YEAR-END>1231
</COMPANY-DATA>
<FILING-VALUES>
<FORM-TYPE>424B3
<ACT>33
<FILE-NUMBER>333-74464
<FILM-NUMBER>04761819
</FILING-VALUES>
<BUSINESS-ADDRESS>
<STREET1>777 OLD SAW MILL RIVER RD
<CITY>TARRYTOWN
<STATE>NY
<ZIP>10591-6707
<PHONE>9143477000
</BUSINESS-ADDRESS>
</FILER>
<DOCUMENT>
<TYPE>424B3
<SEQUENCE>1
<FILENAME>y96793b3e424b3.htm
<DESCRIPTION>PROSPECTUS SUPPLEMENT NO. 9
<TEXT>
<HTML>
<HEAD>
<TITLE>PROSPECTUS SUPPLEMENT NO. 9</TITLE>
</HEAD>
<BODY bgcolor="#FFFFFF">
<!-- PAGEBREAK -->
<H5 align="left" style="page-break-before:always">&nbsp;</H5><P>

<P align="right">
<B>Filed pursuant to Rule&nbsp;No.&nbsp;424(b)(3)</B>

<DIV align="right">
<B>File Number&nbsp;333-74464</B>
</DIV>

<DIV>&nbsp;</DIV>

<!-- link1 "PROSPECTUS SUPPLEMENT NO. 9 Regeneron Pharmaceuticals, Inc. $200,000,000 5.50% Convertible Senior Subordinated Notes due 2008 and Shares of Common Stock Issuable upon Conversion of the Notes" -->

<P align="center">
<B>PROSPECTUS SUPPLEMENT NO. 9</B>

<DIV align="center">
<B>Regeneron Pharmaceuticals, Inc.</B>
</DIV>

<P align="center">
<B>$200,000,000</B>

<DIV align="center">
<B>5.50% Convertible Senior Subordinated Notes due 2008</B>
</DIV>

<DIV align="center">
<B>and Shares of Common Stock Issuable upon Conversion of the
Notes</B>
</DIV>

<P align="left">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
This prospectus supplement supplements the prospectus dated
January&nbsp;24, 2002 of Regeneron Pharmaceuticals, Inc.
relating to the sale by certain of our securityholders
(including their pledges, donees, assignees, transferees,
successors and others who later hold any of the
securityholders&#146; interests) of up to $200,000,000 principal
amount at maturity of notes and the shares of common stock
issuable upon conversion of the notes. You should read this
prospectus supplement in conjunction with the prospectus, and
this prospectus supplement is qualified by reference to the
prospectus, except to the extent that the information in this
prospectus supplement supersedes the information contained in
the prospectus.

<P align="left">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
The table of selling securityholders contained in the prospectus
is hereby modified to add as follows:

<CENTER>
<TABLE width="100%" align="center" cellspacing="0" cellpadding="0" border="0">

<TR>
    <TD width="35%"><FONT size="2">&nbsp;</FONT></TD>
    <TD width="3%"><FONT size="2">&nbsp;</FONT></TD>
    <TD width="8%"><FONT size="2">&nbsp;</FONT></TD>
    <TD width="1%"><FONT size="2">&nbsp;</FONT></TD>
    <TD width="7%"><FONT size="2">&nbsp;</FONT></TD>
    <TD width="3%"><FONT size="2">&nbsp;</FONT></TD>
    <TD width="5%"><FONT size="2">&nbsp;</FONT></TD>
    <TD width="1%"><FONT size="2">&nbsp;</FONT></TD>
    <TD width="5%"><FONT size="2">&nbsp;</FONT></TD>
    <TD width="3%"><FONT size="2">&nbsp;</FONT></TD>
    <TD width="7%"><FONT size="2">&nbsp;</FONT></TD>
    <TD width="1%"><FONT size="2">&nbsp;</FONT></TD>
    <TD width="6%"><FONT size="2">&nbsp;</FONT></TD>
    <TD width="3%"><FONT size="2">&nbsp;</FONT></TD>
    <TD width="5%"><FONT size="2">&nbsp;</FONT></TD>
    <TD width="3%"><FONT size="2">&nbsp;</FONT></TD>
    <TD width="4%"><FONT size="2">&nbsp;</FONT></TD>
</TR>

<TR>
    <TD></TD>
    <TD></TD>
    <TD colspan="3" align="center" nowrap><B><FONT size="2">Aggregate Principal</FONT></B></TD>
    <TD></TD>
    <TD colspan="3"></TD>
    <TD></TD>
    <TD colspan="3" align="center" nowrap><B><FONT size="2">Number of Shares</FONT></B></TD>
    <TD></TD>
    <TD colspan="3" align="center" nowrap><B><FONT size="2">Percentage of</FONT></B></TD>
</TR>

<TR>
    <TD></TD>
    <TD></TD>
    <TD colspan="3" align="center" nowrap><B><FONT size="2">Amount at</FONT></B></TD>
    <TD></TD>
    <TD colspan="3" align="center" nowrap><B><FONT size="2">Percentage of</FONT></B></TD>
    <TD></TD>
    <TD colspan="3" align="center" nowrap><B><FONT size="2">of Common Stock</FONT></B></TD>
    <TD></TD>
    <TD colspan="3" align="center" nowrap><B><FONT size="2">Shares of</FONT></B></TD>
</TR>

<TR>
    <TD></TD>
    <TD></TD>
    <TD colspan="3" align="center" nowrap><B><FONT size="2">Maturity of Notes</FONT></B></TD>
    <TD></TD>
    <TD colspan="3" align="center" nowrap><B><FONT size="2">Notes</FONT></B></TD>
    <TD></TD>
    <TD colspan="3" align="center" nowrap><B><FONT size="2">that may</FONT></B></TD>
    <TD></TD>
    <TD colspan="3" align="center" nowrap><B><FONT size="2">Common Stock</FONT></B></TD>
</TR>

<TR>
    <TD align="center" nowrap><B><FONT size="2">Name</FONT></B></TD>
    <TD></TD>
    <TD colspan="3" align="center" nowrap><B><FONT size="2">that may be Sold</FONT></B></TD>
    <TD></TD>
    <TD colspan="3" align="center" nowrap><B><FONT size="2">Outstanding</FONT></B></TD>
    <TD></TD>
    <TD colspan="3" align="center" nowrap><B><FONT size="2">be Sold(1)</FONT></B></TD>
    <TD></TD>
    <TD colspan="3" align="center" nowrap><B><FONT size="2">Outstanding(2)</FONT></B></TD>
</TR>

<TR>
    <TD align="center" nowrap><HR size="1" noshade></TD>
    <TD></TD>
    <TD colspan="3" align="center" nowrap><HR size="1" noshade></TD>
    <TD></TD>
    <TD colspan="3" align="center" nowrap><HR size="1" noshade></TD>
    <TD></TD>
    <TD colspan="3" align="center" nowrap><HR size="1" noshade></TD>
    <TD></TD>
    <TD colspan="3" align="center" nowrap><HR size="1" noshade></TD>
</TR>

<TR>
    <TD align="left" valign="top">
    <DIV style="margin-left:10px; text-indent:-10px">
    <FONT size="2">CIBC World Markets
    </FONT></DIV>
    </TD>
    <TD><FONT size="2">&nbsp;</FONT></TD>
    <TD align="right" valign="bottom"><FONT size="2">$</FONT></TD>
    <TD align="right" valign="bottom" nowrap><FONT size="2">2,500,000</FONT></TD>
    <TD><FONT size="2">&nbsp;</FONT></TD>
    <TD><FONT size="2">&nbsp;</FONT></TD>
    <TD><FONT size="2">&nbsp;</FONT></TD>
    <TD align="right" valign="bottom" nowrap><FONT size="2">1.25</FONT></TD>
    <TD align="left" valign="bottom" nowrap><FONT size="2">%</FONT></TD>
    <TD><FONT size="2">&nbsp;</FONT></TD>
    <TD><FONT size="2">&nbsp;</FONT></TD>
    <TD align="right" valign="bottom" nowrap><FONT size="2">82,641</FONT></TD>
    <TD><FONT size="2">&nbsp;</FONT></TD>
    <TD><FONT size="2">&nbsp;</FONT></TD>
    <TD><FONT size="2">&nbsp;</FONT></TD>
    <TD align="right" valign="bottom" nowrap><FONT size="2">*</FONT></TD>
    <TD><FONT size="2">&nbsp;</FONT></TD>
</TR>

</TABLE>
</CENTER>

<P align="left">
<HR size="1" width="18%" align="left" noshade>
<P>

<TABLE width="100%" border="0" cellpadding="0" cellspacing="0">

<TR>
    <TD width="2%"></TD>
    <TD width="98%"></TD>
</TR>

<TR valign="top">
    <TD>*&nbsp;</TD>
    <TD align="left">
    Less than one percent (1%).</TD>
</TR>

</TABLE>
<P>

<TABLE width="100%" border="0" cellpadding="0" cellspacing="0">

<TR>
    <TD width="4%"></TD>
    <TD width="96%"></TD>
</TR>

<TR valign="top">
    <TD>(1)&nbsp;</TD>
    <TD align="left">
    Assumes conversion of all of the holder&#146;s notes at a
    conversion rate of 33.0565 shares of common stock per $1,000
    principal amount at maturity of the notes. This conversion rate
    is subject to adjustment, however, as described under
    &#147;Description of the Notes&nbsp;&#151; Conversion of the
    Notes.&#148; As a result, the number of shares of common stock
    issuable upon conversion of the notes may increase or decrease
    in the future.</TD>
</TR>

<TR>
    <TD>&nbsp;</TD>
</TR>

<TR valign="top">
    <TD>(2)&nbsp;</TD>
    <TD align="left">
    Calculated based on Rule&nbsp;13d-3(d)(i) of the Exchange Act,
    using 53,197,081 shares of common stock outstanding as of
    December&nbsp;31, 2003. In calculating this amount for each
    holder, we treated as outstanding the number of shares of common
    stock issuable upon conversion of all that holder&#146;s notes,
    but we did not assume conversion of any other holder&#146;s
    notes.</TD>
</TR>

</TABLE>

<P align="left">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
Investing in the notes or shares of common stock involves risks
that are described in the &#147;Risk Factors&#148; section
beginning on page&nbsp;5 of the prospectus.

<P align="left">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
<B>Neither the Securities and Exchange Commission nor any state
securities commission has approved or disapproved of these
securities or determined if this prospectus supplement is
truthful or complete. Any representation to the contrary is a
criminal offense.</B>

<P align="left">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
The date of this prospectus supplement is April&nbsp;28, 2004
</BODY>
</HTML>

</TEXT>
</DOCUMENT>
</SUBMISSION>
