EXHIBIT 31.1

                                 CERTIFICATIONS

I, John R. Irwin, certify that:

        1.    I have reviewed this quarterly report on Form 10-Q of Atwood
              Oceanics, 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)) and internal control over financial
              reporting (as defined in Exchange Act Rules 13a-15(f) and
              15d-15(f)) 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) Designed such internal control over financial reporting,
              or caused such internal control over financial reporting to be
              designed under our supervision, to provide reasonable
              assurance regarding the reliability of financial reporting and
              the preparation of financial statements for external purposes
              in accordance with generally accepted accounting principles;

              (c) 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

              (d) 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: May 9, 2007

                  /s/ JOHN R. IRWIN
                  John R. Irwin
                  Chief Executive Officer