Ex. 99.1

                       [ATWOOD OCEANICS, INC. LETTERHEAD]

                                 April 7, 2006

Dear Shareholder:

         We are pleased to enclose a stock certificate representing additional
shares of the Common Stock as well as Rights (as defined below) associated with
such shares (collectively, the "Shares") of Atwood Oceanics, Inc. (the
"Company") to which you are entitled as a result of the two-for-one stock split
effected as a 100% stock dividend. This new certificate represents one
additional Share for each Share of Common Stock held by you as of the close of
business on March 24, 2006, the record date for the stock split. ANY STOCK
CERTIFICATE HELD BY YOU PRIOR TO THE STOCK SPLIT IS STILL VALID, REPRESENTING
THE NUMBER OF SHARES STATED THEREON, AND DOES NOT NEED TO BE EXCHANGED FOR A
NEW CERTIFICATE. DO NOT DESTROY OR RETURN TO THE COMPANY ANY STOCK CERTIFICATES
IN YOUR POSSESSION.

         The Company's Board of Directors believes that a stock split in the
form of a stock dividend is in the best interests of shareholders. A transfer
of $1.00 for each additional Share issued, or $15,451,586 in the aggregate, was
made from the Company's additional paid-in capital account to its Common Stock
account on the record date of March 24, 2006. Both current earnings and
retained earnings of the Company exceed the aggregate amount capitalized as a
result of the distribution. Any sale of the Shares issued pursuant to the
distribution will result in a reduction of your proportionate equity interest
in the Company.

         Notice Regarding Rights Agreement: In accordance with the Rights
Agreement dated as of October 18, 2002 (the "Rights Agreement"), between the
Company and Continental Stock Transfer & Trust Company, as Rights Agent, in
order to reflect the stock split each share of outstanding Common Stock
(including the shares issued in connection with the stock split) will be
accompanied by the right to purchase one two-thousandth of a share of Series A
Junior Participating Preferred Stock (a "Right"). In addition, the redemption
price of each Right will be decreased by one-half from $0.01 to $0.005 in
connection with the Stock Split. The Rights Agreement was filed as Exhibit 4.1
to the Company's Registration Statement on Form 8-A filed with the Securities
and Exchange Commission on October 21, 2002 (File No. 001-13167). Reference is
made to the Rights Agreement, the Form 8-A referenced above and any amendments
thereto for a more complete description of the terms of the Rights and the
adjustments made in connection with the stock split.

         Any questions about share transfer requirements, lost certificates or
address changes may be directed to the Company's transfer agent and registrar
of the Company's Common Stock as follows:

                   Continental Stock Transfer & Trust Company
                                17 Battery Place
                            New York, NY 10004-1123

         We appreciate your continued interest and your continued support of
the Company.

                               Very truly yours,



                                 John R. Irwin
                                 President