<PAGE>

                                  EXHIBIT 31.1
                                 CERTIFICATIONS

I, Munawar Hidayatallah, Chief Executive Officer of the Company, certify that:

      1. I have reviewed this Annual Report on Form 10-K of Allis-Chalmers
Energy Inc.:

      2. Based on my knowledge, this report does not contain any untrue
statement of a material fact or omit to state a material fact necessary to make
the statements made, in light of the circumstances under which such statements
were made, not misleading with respect to the period covered by this report;

      3. Based on my knowledge, the financial statements, and other financial
information included in this report, fairly present in all material respects the
financial condition, results of operations and cash flows of the registrant as
of, and for, the periods presented in this report;

      4. The registrant's other certifying officer(s) and I are responsible for
establishing and maintaining disclosure controls and procedures (as defined in
Exchange Act Rules 13a-15(e) and 15d-15(e)) for the registrant and have:

            (a) Designed such disclosure controls and procedures, or caused such
disclosure controls and procedures to be designed under our supervision, to
ensure that material information relating to the registrant, including its
consolidated subsidiaries, is made known to us by others within those entities,
particularly during the period in which this report is being prepared;

            (b) Evaluated the effectiveness of the registrant's disclosure
controls and procedures and presented in this report our conclusions about the
effectiveness of the disclosure controls and procedures, as of the end of the
period covered by this report based on such evaluation;

            (c) Disclosed in this report any change in the registrant's internal
control over financial reporting that occurred during the registrant's most
recent fiscal quarter (the registrant's fourth fiscal quarter in the case of an
annual report) that has materially affected, or is reasonably likely to
materially affect, the registrant's internal control over financial reporting;
and

      5. The registrant's other certifying officer(s) and I have disclosed,
based on our most recent evaluation of internal control over financial
reporting, to the registrant's auditors and the audit committee of the
registrant's board of directors (or persons performing the equivalent
functions):

            (a) All significant deficiencies and material weaknesses in the
design or operation of internal control over financial reporting which are
reasonably likely to adversely affect the registrant's ability to record,
process, summarize and report financial information; and

            (b) Any fraud, whether or not material, that involves management or
other employees who have a significant role in the registrant's internal control
over financial reporting.

           DATE: APRIL 13, 2005      BY:   /S/ MUNAWAR H. HIDAYATALLAH
                                           ------------------------------
                                           MUNAWAR H. HIDAYATALLAH
                                           CHIEF EXECUTIVE OFFICER

                                       70



<PAGE>

                                  EXHIBIT 31.2
                                 CERTIFICATIONS

I, Victor M. Perez, Chief Financial Officer of the Company, certify that:

      1. I have reviewed this Annual Report on Form 10-K of Allis-Chalmers
Energy Inc.;

      2. Based on my knowledge, this report does not contain any untrue
statement of a material fact or omit to state a material fact necessary to make
the statements made, in light of the circumstances under which such statements
were made, not misleading with respect to the period covered by this report;

      3. Based on my knowledge, the financial statements, and other financial
information included in this report, fairly present in all material respects the
financial condition, results of operations and cash flows of the registrant as
of, and for, the periods presented in this report;

      4. The registrant's other certifying officer(s) and I are responsible for
establishing and maintaining disclosure controls and procedures (as defined in
Exchange Act Rules 13a-15(e) and 15d-15(e)) for the registrant and have:

             (a) Designed such disclosure controls and procedures, or caused
such disclosure controls and procedures to be designed under our supervision, to
ensure that material information relating to the registrant, including its
consolidated subsidiaries, is made known to us by others within those entities,
particularly during the period in which this report is being prepared;

             (b) Evaluated the effectiveness of the registrant's disclosure
controls and procedures and presented in this report our conclusions about the
effectiveness of the disclosure controls and procedures, as of the end of the
period covered by this report based on such evaluation; and

             (c) Disclosed in this report any change in the registrant's
internal control over financial reporting that occurred during the registrant's
most recent fiscal quarter (the registrant's fourth fiscal quarter in the case
of an annual report) that has materially affected, or is reasonably likely to
materially affect, the registrant's internal control over financial reporting;

      5. The registrant's other certifying officer(s) and I have disclosed,
based on our most recent evaluation of internal control over financial
reporting, to the registrant's auditors and the audit committee of the
registrant's board of directors (or persons performing the equivalent
functions):

             (a) All significant deficiencies and material weaknesses in the
design or operation of internal control over financial reporting which are
reasonably likely to adversely affect the registrant's ability to record,
process, summarize and report financial information; and

             (b) Any fraud, whether or not material, that involves management or
other employees who have a significant role in the registrant's internal control
over financial reporting.

             DATE: APRIL 13, 2005      BY:       /S/ VICTOR M. PEREZ
                                             -------------------------------
                                             VICTOR M. PEREZ
                                             CHIEF FINANCIAL OFFICER

                                       71







<PAGE>

                                  EXHIBIT 32.1

                CERTIFICATION PURSUANT TO 18 U.S.C. SECTION 1350,
                             AS ADOPTED PURSUANT TO
                  SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Annual Report on Form 10-K of Allis-Chalmers Corporation.
(the "Company") for the period ended December 31, 2004, as filed with the
Securities and Exchange Commission on the date hereof (the "Report"), the
undersigned hereby certify, pursuant to 18 U.S.C. Section 1350, that:

(1) The Report fully complies with the requirements of Section 13(a) or 15(d) of
the Securities Exchange Act of 1934; and

(2) The information contained in the Report fairly presents, in all material
respects, the financial condition and results of the operations of the Company.


DATE: APRIL 13, 2005 BY:       /S/ MUNAWAR H. HIDAYATALLAH
                               ----------------------------------
                               MUNAWAR H. HIDAYATALLAH
                             CHIEF EXECUTIVE OFFICER

DATE: APRIL 13, 2005 BY:       /S/ VICTOR M. PEREZ
                               ----------------------------------
                               VICTOR M. PEREZ
                             CHIEF FINANCIAL OFFICER

                                       72