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UNITED STATES SECURITIES AND EXCHANGE
COMMISSION

Washington, D.C. 20549


Amendment No. 3 to Form 10-K on

Form 10-K/A

|  |  |                                                                                             
|- |  | --------------------------------------------------------------------------------------------
|þ |  | ANNUAL REPORT PURSUANT TO SECTION 13 OR
    15(d) OF THE SECURITIES EXCHANGE ACT OF 1934    
| 
|  |  | For the Fiscal Year Ended December 31,
    2003                                             
| 
|o |  | TRANSITION REPORT PURSUANT TO SECTION 13
    OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934
| 
|  |  | For the transition period
    from           to                                             

Commission file number: 001-15423

Grant Prideco, Inc.

(Exact name of registrant as specified in its
charter)


|                                                                                                      |  |                                                   
|----------------------------------------------------------------------------------------------------- |  | --------------------------------------------------
|Delaware(State or Other Jurisdiction
    of Incorporation or Organization)                            |  | 76-0312499(I.R.S. Employer
    Identification No.)
|                                                                                                     
|400 N. Sam Houston Pkway
    Suite 900
    Houston, Texas(Address of Principal Executive
    Offices) |  | 77060(Zip Code)                                   

(281) 878-8000

(Registrants telephone number, including
area code)


Securities to be 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 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 þ          No o

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.     þ

Indicate by check mark whether the registrant is
an accelerated filer (as defined in Exchange Act
Rule 12b-2).     Yes þ          No o

Aggregate market value of Common Stock held by
nonaffiliates as of June 30, 2003: $1,408,228,676

Number of shares of Common Stock outstanding as
of March 2, 2004: 121,717,532

DOCUMENTS INCORPORATED BY REFERENCE

Listed below is the document parts of which are
incorporated herein by reference and the part of this report
into which the document is incorporated:

(1) Proxy Statement for 2004 Annual Meeting
of Stockholders  Part III



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FORM 10-K

Explanatory Note

This Amendment No. 3 to the Annual Report on
Form 10-K for the year ended December 31, 2003, is
being filed solely to amend the form of certifying language
contained in Exhibits 31.1 and 31.2 included herein. This
amendment does not otherwise update any other exhibits as
originally filed and does not otherwise reflect events occurring
after the original filing date of the Annual Report on
Form 10-K for the year ended December 31, 2003.



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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.



| |                    
| | -------------------
| | GRANT PRIDECO, INC.



| |     |                    
| | --- | -------------------
| | By: | /s/ MICHAEL MCSHANE

| |                                    
| | -----------------------------------
| |                                    
| | Michael McShane                    
| | Chief Executive Officer, President,
| | and Chairman of the Board          

Date: February 15, 2005

Pursuant to the requirements of the Securities
Exchange Act of 1934, this report has been signed below by the
following individuals on behalf of the registrant and in the
capacities and on the dates indicated.

|                                               |  |                                                                                                    |  |                   |  | 
|---------------------------------------------- |  | -------------------------------------------------------------------------------------------------- |  | ----------------- |  | 
|                                               |  |                                                                                                    |  |                  
|Signature                                      |  | Capacity in Which Signed                                                                           |  | Date             
|                                               |  |                                                                                                    |  |                  
|                                              
|/s/ MICHAEL MCSHANEMichael McShane             |  | Chief Executive Officer, President and Chairman
    of the Board
    (Principal Executive Officer) |  | February 15, 2005
|                                              
|/s/ MATTHEW D. FITZGERALDMatthew D. Fitzgerald |  | Senior Vice President and Chief Financial
    Officer
    (Principal Financial Officer)            |  | February 15, 2005
|                                              
|/s/ GREG L. BOANEGreg L. Boane                 |  | Corporate Controller
    (Principal Accounting Officer)                                            |  | February 15, 2005



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INDEX TO EXHIBITS

| |    |    |  |                                        
| | -- | -- |  | ---------------------------------------
| | 31 | .1 |  | Certification of Michael McShane.      
| | 31 | .2 |  | Certification of Matthew D. Fitzgerald.