1

                                  UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                               Washington DC 20549

                                   FORM 10-Q/A
                                 AMENDMENT NO. 2

/X/      QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES
         EXCHANGE ACT OF 1934

For the quarterly period ended        June 30, 2004
                               -------------------------------------------------

                                       OR

/ /      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       1-9887
                       --------------------

                            OREGON STEEL MILLS, INC.
--------------------------------------------------------------------------------
             (Exact name of registrant as specified in its charter)

  Delaware                                                  94-0506370
--------------------------------------------------------------------------------
   (State or other jurisdiction of                         (IRS Employer
    incorporation or organization)                          Identification No.)

   1000 S.W. Broadway, Suite 2200, Portland, Oregon            97205
--------------------------------------------------------------------------------
(Address of principal executive offices)                     (Zip Code)

                                 (503) 223-9228
-------------------------------------------------------------------------------
              (Registrant's telephone number, including area code)


(Former name, former address and former fiscal year, if changed since last
 report)

         Indicate by check mark whether the registrant (1) has filed all reports
required to be filed by Sections 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 X        No
                                                     ---         ---

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

Indicate the number of shares outstanding of each of the issuer's classes of
common stock, as of the latest practicable date:

         Common Stock, $.01 Par Value                    26,677,504
         ----------------------------             ------------------------------
                     Class                        Number of Shares Outstanding
                                                       (as of July 31, 2004)



<PAGE>

                                 EXPLANATORY NOTE:

This Amendment No. 2 on Form 10-Q/A ("Amendment No. 2") is filed to add this
Explanatory Note which should have accompanied Amendment No. 1 on Form 10-Q /A
of Oregon Steel Mills, Inc. filed September 14, 2004 ("Amendment No. 1").
Amendment No. 1 was filed to amend limited sections of the Oregon Steel Mills,
Inc. Form 10-Q for the quarter ended June 30, 2004 filed August 9, 2004,
including limited changes regarding the number of shares outstanding as of July
31, 2004, Net Income (Loss) per Share, and certain figures in the Consolidated
Balance Sheet and Consolidated Statements of Operations, as well as to amplify
statements regarding RMSM environmental matters.

Oregon Steel Mills, Inc. believes the changes are not material, but reflect
typing, rounding and conforming corrections.

This Amendment No. 2 also amends Part II, Item 6 to include new certifications
of the principal executive officer and principal financial officer in accordance
with Rule 12b-15.




                                   SIGNATURES

Pursuant to the requirements 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.


                            OREGON STEEL MILLS, INC.
--------------------------------------------------------------------------------
                                  (Registrant)



Date:   September 17, 2004                 By:  /s/ Jeff S. Stewart
      ----------------------------            -------------------------------
                                               Jeff S. Stewart
                                               Corporate Controller
                                               (Principal Accounting Officer)