UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D. C. 20549

FORM 10-K/A

þANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE

SECURITIES EXCHANGE ACT OF 1934

For the fiscal year ended December 31, 2009

OR

 ̈    TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE

SECURITIES EXCHANGE ACT OF 1934

Commission file number: 001-31470

PLAINS EXPLORATION & PRODUCTION COMPANY

(Exact name of registrant as specified in its charter)



|                                |  |                    
|------------------------------- |  | -------------------
|Delaware                        |  | 33-0430755         
|(State or other jurisdiction of |  | (I.R.S. Employer   
|incorporation or organization)  |  | Identification No.)

700 Milam Street,
Suite 3100

Houston, Texas 77002

(Address of principal executive offices)

(Zip Code)

(713) 579-6000

(Registrants telephone number, including area code)

Securities registered pursuant to Section 12(b) of the Act:



|                                        |  |                                          
|--------------------------------------- |  | -----------------------------------------
|Title of each class                     |  | Name of each exchange on which registered
|Common Stock, par value $0.01 per share |  | New York Stock Exchange                  

Securities
registered pursuant to Section 12(g) of the Act: none

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in
Rule 405 of the Securities
Act.    Yes   ü    
No

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or
Section 15(d) of the Act.    Yes      No   ü

Indicate by check mark whether the registrant (1) has filed all reports required to be
filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for
the past 90
days.    Yes   ü    
No

Indicate by check mark whether the registrant has submitted electronically and posted on its
corporate website, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such
files).    Yes   ü   
 No

Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of
Regulation S-K is not contained herein, and will not be contained, to the best of registrants knowledge, in definitive proxy or information statements incorporated by reference in Part III of this Form 10-K or any amendment to this Form
10-K.       ü

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer or a smaller reporting company. See the
definitions of large accelerated filer, accelerated filer, and smaller reporting company in Rule 12b-2 of the Exchange Act. (Check one):

ü  Large accelerated
filer  Accelerated filer  Non-accelerated
filer  (Do not check if a smaller reporting company)  Smaller reporting company

Indicate by check mark whether the registrant is a shell company (as defined in Exchange Act Rule
12b-2).    Yes      No   
ü

The aggregate market value of the Common Stock held by non-affiliates of the registrant (treating all executive officers and directors of the registrant, for this
purpose, as if they may be affiliates of the registrant) was approximately $3.3 billion on June 30, 2009 (based on $27.36 per share, the last sale price of the Common Stock as reported on the New York Stock Exchange on such date). On
January 29, 2010, there were 139.4 million shares of the registrants Common Stock outstanding.

DOCUMENTS INCORPORATED BY
REFERENCE: The information required in Part III of the Annual Report on Form 10-K is incorporated by reference to the registrants definitive proxy statement to be filed pursuant to Regulation 14A for the registrants 2010 Annual
Meeting of Stockholders.









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EXPLANATORY NOTE

Plains Exploration & Production Company, or PXP, is filing this Amendment No. 1 to our Form 10-K for the year ended
December 31, 2009 originally filed with the Securities and Exchange Commission on February 25, 2010, or the 2009 Form 10-K, solely for the purpose of filing revised reports from one of our third-party petroleum engineering firms. The
reports from Ryder Scott Company, L.P., or Ryder Scott, were filed as Exhibit 99.3 and 99.4 to the 2009 Form 10-K. In addition to the revised reports being filed as Exhibit 99.3 and 99.4, we are including in this Form 10-K/A a consent from Ryder
Scott in Exhibit 23.3 and certifications of our principal executive officer and principal financial officer in Exhibit 31.1 and 31.2.

No item of or disclosures appearing in our 2009 Form 10-K are affected by this filing other than the exhibits described above. This report on Form
10-K/A is presented as of the filing date of the 2009 Form 10-K and does not reflect events occurring after that date, or modify or update disclosures in any way.



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PART IV

Item 15.Exhibits, Financial Statement Schedules

(a) (3) Exhibits



|               |  |                                                                        
|-------------- |  | -----------------------------------------------------------------------
|Exhibit
Number |  | Description                                                            
|               | 
|23.3*          |  | Consent of Ryder Scott Company, L.P.                                   
|               | 
|31.1*          |  | Rule 13(a)-14(a)/15d-14(a) Certificate of the Chief Executive Officer. 
|               | 
|31.2*          |  | Rule 13(a)-14(a)/15d-14(a) Certificate of the Chief Financial Officer. 
|               | 
|99.3*          |  | Report of Ryder Scott Company, L.P., Certain Gulf of Mexico Properties.
|               | 
|99.4*          |  | Report of Ryder Scott Company, L.P., Panhandle Properties.             



|* | Filed herewith.
|- | ---------------



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SIGNATURES

Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the registrant has duly caused this report to be
signed on its behalf by the undersigned, thereunto duly authorized.



|                        |  |                                                                                                       
|----------------------- |  | ------------------------------------------------------------------------------------------------------
|                        |  | PLAINS EXPLORATION & PRODUCTION COMPANY                                                               
|                        | 
|Date: September 1, 2010 |  | /s/ Winston M. Talbert                                                                                
|                        |  | Winston M. Talbert, Executive Vice President and Chief Financial Officer (Principal Financial Officer)



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EXHIBIT INDEX



|               |  |                                                                        
|-------------- |  | -----------------------------------------------------------------------
|Exhibit
Number |  | Description                                                            
|               | 
|23.3*          |  | Consent of Ryder Scott Company, L.P.                                   
|               | 
|31.1*          |  | Rule 13(a)-14(a)/15d-14(a) Certificate of the Chief Executive Officer. 
|               | 
|31.2*          |  | Rule 13(a)-14(a)/15d-14(a) Certificate of the Chief Financial Officer. 
|               | 
|99.3*          |  | Report of Ryder Scott Company, L.P., Certain Gulf of Mexico Properties.
|               | 
|99.4*          |  | Report of Ryder Scott Company, L.P., Panhandle Properties.             



|* | Filed herewith.
|- | ---------------