<SUBMISSION>
<ACCESSION-NUMBER>0001019687-05-002611
<TYPE>S-3
<PUBLIC-DOCUMENT-COUNT>5
<FILING-DATE>20050916
<DATE-OF-FILING-DATE-CHANGE>20050916
<FILER>
<COMPANY-DATA>
<CONFORMED-NAME>ACACIA RESEARCH CORP
<CIK>0000934549
<ASSIGNED-SIC>3670
<IRS-NUMBER>954405754
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>1231
</COMPANY-DATA>
<FILING-VALUES>
<FORM-TYPE>S-3
<ACT>33
<FILE-NUMBER>333-128359
<FILM-NUMBER>051087731
</FILING-VALUES>
<BUSINESS-ADDRESS>
<STREET1>500 NEWPORT CENTER DRIVE
<STREET2>7TH FLOOR
<CITY>NEWPORT BEACH
<STATE>CA
<ZIP>92660
<PHONE>9494808300
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>500 NEWPORT CENTER DRIVE
<STREET2>#
<CITY>NEWPORT BEACH
<STATE>CA
<ZIP>92660
</MAIL-ADDRESS>
</FILER>
<DOCUMENT>
<TYPE>S-3
<SEQUENCE>1
<FILENAME>acacia_s3-091505.txt
<TEXT>
<PAGE>

   AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON SEPTEMBER 15, 2005
                              REGISTRATION NO. 333-
      =====================================================================
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
                               ___________________

                                    FORM S-3
             REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933
                               ___________________

                           ACACIA RESEARCH CORPORATION
             (Exact Name of Registrant as Specified in Its Charter)
                               ___________________

             DELAWARE                                            95-4405754
   (State or other jurisdiction                              (I.R.S. Employer
of incorporation or organization)                        Identification Number)

                       500 NEWPORT CENTER DRIVE, 7TH FLOOR
                         NEWPORT BEACH, CALIFORNIA 92660
                                 (949) 480-8300
   (Address, including zip code, and telephone number, including area code of
                   registrant's principal executive offices)
                               ___________________

                                  PAUL R. RYAN
                             CHIEF EXECUTIVE OFFICER
                       500 NEWPORT CENTER DRIVE, 7TH FLOOR
                         NEWPORT BEACH, CALIFORNIA 92660
                                 (949) 480-8300
(Address, including zip code, and telephone number, including area code of agent
                                  for service)
                               ___________________

                                   Copies to:
                              RAYMOND A. LEE, ESQ.
                             GREENBERG TRAURIG, LLP
                        650 TOWN CENTER DRIVE, SUITE 1700
                          COSTA MESA, CALIFORNIA 92626
                                 (714) 708-6500
                               ___________________

         Approximate date of commencement of proposed sale to the public: From
time to time after the effective date of this Registration Statement.

         If the only securities being registered on this form are being offered
pursuant to dividend or interest reinvestment plans, please check the following
box. [ ]

         If any of the securities being registered on this Form are to be
offered on a delayed or continuous basis pursuant to Rule 415 under the
Securities Act of 1933, other than securities offered only in connection with
dividend or interest reinvestment plans, check the following box. [X]

         If this Form is filed to register additional securities for an offering
pursuant to Rule 462(b) under the Securities Act, check the following box and
list the Securities Act registration statement number of the earlier effective
registration statement for the same offering. [X] 333-112885

         If this Form is a post-effective amendment filed pursuant to Rule
462(c) under the Securities Act, check the following box and list the Securities
Act registration number of the earlier effective registration statement for the
same offering. [ ]

         If delivery of the prospectus is expected to be made pursuant to Rule
434, please check the following box. [ ]


<PAGE>
<TABLE>

                                     CALCULATION OF REGISTRATION FEE

-------------------------------------------- --------------------- ------------------- --------------------
                                               PROPOSED MAXIMUM     PROPOSED MAXIMUM        AMOUNT OF
 TITLE OF SECURITIES TO BE REGISTERED (1)     AGGREGATE OFFERING     OFFERING PRICE     REGISTRATION FEE
                                                PRICE (1) (2)         PER UNIT (3)
-------------------------------------------- --------------------- ------------------- --------------------
<S>                                          <C>
Acacia Research-CombiMatrix Common Stock,             __                   __                  __
$0.001 par value per share..................
-------------------------------------------- --------------------- ------------------- --------------------
Warrants to purchase Acacia                           __                   __                  __
Research-CombiMatrix Common Stock...........
-------------------------------------------- --------------------- ------------------- --------------------
Total.......................................    $2,449,800(4)             100%               $288.34
-------------------------------------------- --------------------- ------------------- --------------------
</TABLE>

(1) The Registrant previously registered securities having a maximum aggregate
offering price of $50,000,000 on a registration statement on Form S-3 (File No.
333-112885) for which a fee of $6,335 was previously paid.

(2) Estimated solely for purposes of calculating the registration fee pursuant
to Rule 457(o) under the Securities Act of 1933.

(3) We will determine the proposed maximum offering price per unit in connection
with the issuance of the new securities.

(4) The securities registered hereunder may be sold separately or as units with
other securities registered hereby. The aggregate amount of common stock
registered hereunder is limited to that which is permissible under Rule
415(a)(4) under the Securities Act of 1933, to the extent applicable.

      =====================================================================


<PAGE>


                                EXPLANATORY NOTE

            This Registration Statement is being filed pursuant to Rule 462(b)
and General Instruction IV to Form S-3, both as promulgated under the Securities
Act of 1933, as amended. The contents of the Registration Statement on Form S-3
(File No. 333-112885) filed by Acacia Research Corporation with the Securities
and Exchange Commission on February 17, 2004, which has been declared effective
by the SEC, which and including the documents filed by Acacia Research
Corporation with the SEC and incorporated or deemed to be incorporated therein,
are incorporated herein by reference.


<PAGE>



                                   SIGNATURES

         Pursuant to the requirements of the Securities Act of 1933, Acacia
Research Corporation certifies that it has reasonable grounds to believe that it
meets all of the requirements for filing on Form S-3 and has duly caused this
registration statement to be signed on its behalf by the undersigned, thereunto
duly authorized, in the City of Newport Beach, State of California, as of
September 15, 2005.



                                        ACACIA RESEARCH CORPORATION

                                        By: /s/ Paul R. Ryan
                                            ------------------------------------
                                            Paul R. Ryan
                                            Chief Executive Officer and Chairman




                                POWER OF ATTORNEY

         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.

<TABLE>
<S>                                      <C>
SIGNATURE                                TITLE                                               DATE
---------                                -----                                               ----
 *                                       Chief Executive Officer and Chairman of the Board   September 15, 2005
-----------------------------------      (Principal Executive Officer)
PAUL R. RYAN

/s/ Clayton J. Haynes                    Chief Financial Officer (Principal Financial and    September 15, 2005
-----------------------------------      Accounting Officer)
CLAYTON J. HAYNES

 *                                       President and Director                              September 15, 2005
-----------------------------------
ROBERT L. HARRIS

 *                                       Director                                            September 15, 2005
-----------------------------------
THOMAS B. AKIN

 *                                       Director                                            September 15, 2005
-----------------------------------
RIGDON CURRIE

 *                                       Director                                            September 15, 2005
-----------------------------------
FRED A. DE BOOM

 *                                       Director                                            September 15, 2005
-----------------------------------
EDWARD W. FRYKMAN

 *                                       Director                                            September 15, 2005
-----------------------------------
G. LOUIS GRAZIADIO III

 *                                       Director                                            September 15, 2005
-----------------------------------
AMIT KUMAR


By: /s/ Clayton J. Haynes
    --------------------------------
Clayton J. Haynes
Attorney-in-Fact
</TABLE>



<PAGE>



                                  EXHIBIT INDEX

         Pursuant to Item 601(a)(2) of Regulation S-K, this exhibit index
immediately precedes the exhibits.

EXHIBIT
NUMBER            DESCRIPTION
------            -----------
5.1               Opinion of Greenberg Traurig, LLP
23.1              Consent of Greenberg Traurig, LLP (contained in their opinion
                   filed as Exhibit 5.1 to this Registration Statement)
23.2              Consent of Independent Registered Public Accounting Firm
23.3              Consent of Independent Registered Public Accounting Firm
23.4              Consent of Independent Registered Public Accounting Firm





</TEXT>
</DOCUMENT>
<DOCUMENT>
<TYPE>EX-5.1
<SEQUENCE>2
<FILENAME>acacia_s3-ex0501.txt
<DESCRIPTION>OPINION
<TEXT>
<PAGE>


                                                                     EXHIBIT 5.1

                  OPINION AND CONSENT OF GREENBERG TRAURIG, LLP

                                                              September 15, 2005

Acacia Research Corporation
500 Newport Center Drive
Newport Beach, California 92660

         Re:      Acacia Research Corporation Registration Statement on Form S-3

Ladies and Gentlemen:


We have acted as counsel to Acacia Research Corporation, a Delaware corporation
(the "Company"), in connection with the filing of a Registration Statement on
Form S-3 (the "Registration Statement") pursuant to Rule 462(b) of Regulation C
promulgated under the Securities Act of 1933, as amended (the "Securities Act"),
relating to the offering and sale by the Company from time to time of shares of
its Combimatrix Common Stock, par value $0.001 per share ("Common Stock"), of
the Company (the "Shares"). The Shares are being registered for offering and
sale from time to time pursuant to Rule 415 of the General Rules and Regulations
promulgated under the Securities Act (the "Securities Act Rules"). The
Registration Statement incorporates by reference the Registration Statement on
Form S-3 (No. 333-112885), which was filed on February 17, 2004 and which has
been declared effective by the Securities and Exchange Commission, including the
prospectus which forms a part of such registration statement (the "Prospectus"),
as supplemented from time to time by one or more prospectus supplements (each, a
"Prospectus Supplement").

In connection with this opinion, we have examined and relied upon the originals,
or copies certified to our satisfaction, of such records, documents,
certificates, opinions, memoranda and other instruments as in our judgment are
necessary or appropriate to enable us to render the opinion expressed below. As
to certain factual matters, we have relied upon certificates of the officers of
the Company and have not sought to independently verify such matters.

In rendering this opinion, we have assumed the genuineness and authenticity of
all signatures on original documents; the authenticity of all documents
submitted to us as originals; the conformity to originals of all documents
submitted to us as copies; the accuracy, completeness and authenticity of
certificates of public officials; and the due authorization, execution and
delivery of all documents where authorization, execution and delivery are
prerequisites to the effectiveness of such documents. We have also assumed that,
at the time of issuance and sale, a sufficient number of shares of Common Stock
is authorized and reserved or available for issuance and that the consideration
for the issuance and sale of the Shares is not less than the aggregate par value
of the Shares, and that, prior to any offering and sale of the Shares, the
Company's board of directors (the "Board"), including any appropriate committee
appointed thereby, will duly authorize the terms of and the prices at which the
Shares are to be issued and sold.

Our opinion herein is expressed solely with respect to the federal laws of the
United States and the Delaware General Corporation Law. We express no opinion as
to whether the laws of any jurisdiction are applicable to the subject matter
hereof. We are not rendering any opinion as to compliance with any federal or
state antifraud law, rule or regulation relating to securities, or to the sale
or issuance thereof.

On the basis of the foregoing and in reliance thereon, and subject to the
qualifications herein stated, we are of the opinion that, with respect to any
offering of the Shares, if (i) the Registration Statement has become effective;
(ii) the Prospectus and any Prospectus Supplement(s) required by applicable laws
have been delivered as required by such laws; (iii) the Shares are to be sold
pursuant to a purchase, underwriting or similar agreement, such purchase,
underwriting or similar agreement has been duly authorized, executed and
delivered by the Company and the other parties thereto and has become a valid
and binding agreement of the Company; (iv) the Board, including any appropriate
committee appointed thereby, and appropriate officers of the Company have taken
all necessary corporate action to approve the issuance and terms of the Shares
and related matters; and (v) the terms of the Shares and of their issuance and
sale have been duly established in conformity with the operative certificate of
incorporation and bylaws of the Company and the Delaware General Corporation Law
so as not to violate any applicable law, the operative certificate of
incorporation or bylaws of the Company or result in a default under or breach of
any agreement or instrument binding upon the Company and so as to comply with
any requirement or restriction imposed by any court or governmental body having
jurisdiction over the Company, then the Shares, when issued and sold in
accordance with a duly authorized, executed and delivered purchase, underwriting
or similar agreement, will be duly authorized, validly issued, fully paid and
nonassessable.

We hereby consent to the filing of this opinion as an exhibit to the
Registration Statement and to the reference to our firm under the caption "Legal
Matters" in the Prospectus included in the Registration Statement.

Very truly yours,


/s/ Greenberg Traurig, LLP
Greenberg Traurig, LLP


</TEXT>
</DOCUMENT>
<DOCUMENT>
<TYPE>EX-23.2
<SEQUENCE>3
<FILENAME>acacia_s3-ex2302.txt
<DESCRIPTION>CONSENT
<TEXT>
<PAGE>


                                                                    EXHIBIT 23.2



            CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We hereby consent to the incorporation by reference in this Registration
Statement on Form S-3 of our report dated March 14, 2005 relating to the
financial statements, management's assessment of the effectiveness of internal
control over financial reporting and the effectiveness of internal control over
financial reporting of Acacia Research Corporation, which appears in Acacia
Research Corporation's Annual Report on Form 10-K for the year ended December
31, 2004.

/s/ PricewaterhouseCoopers LLP

Los Angeles, California
September 15, 2005


</TEXT>
</DOCUMENT>
<DOCUMENT>
<TYPE>EX-23.3
<SEQUENCE>4
<FILENAME>acacia_s3-ex2303.txt
<DESCRIPTION>CONSENT
<TEXT>
<PAGE>


                                                                    EXHIBIT 23.3

            CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We hereby consent to the incorporation by reference in this Registration
Statement on Form S-3 of our report dated March 14, 2005 relating to the
financial statements of Acacia Technologies Group (a division of Acacia Research
Corporation), which appears in Acacia Research Corporation's Annual Report on
Form 10-K for the year ended December 31, 2004.

/s/ PricewaterhouseCoopers LLP

Los Angeles, California
September 15, 2005


</TEXT>
</DOCUMENT>
<DOCUMENT>
<TYPE>EX-23.4
<SEQUENCE>5
<FILENAME>acacia_s3-ex2304.txt
<DESCRIPTION>CONSENT
<TEXT>
<PAGE>



                                                                    EXHIBIT 23.4


            CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We hereby consent to the incorporation by reference in this Registration
Statement on Form S-3 of our report dated March 14, 2005 relating to the
financial statements of CombiMatrix Group (a division of Acacia Research
Corporation), which appears in Acacia Research Corporation's Annual Report on
Form 10-K for the year ended December 31, 2004.

/s/ PricewaterhouseCoopers LLP

Los Angeles, California
September 15, 2005


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