EXHIBIT 31.1

                                 CERTIFICATIONS

I, John R. Irwin, certify that:

         1.       I have reviewed this annual report on Form 10-K 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
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                  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: December 13, 2006

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