¨

Preliminary proxy statement

¨

¨

Definitive proxy statement

x

Definitive additional materials

¨

Soliciting material pursuant to § 240.14a-12.

Payment of filing fee (check the appropriate box):

x

No fee required.

¨

Fee computed on table below per Exchange Act Rules 14a-6(i)(1) and 0-11.

(1)

Title of each class of securities to which transaction applies:

(2)

Aggregate number of securities to which transaction applies:

(3)

Per unit price or other underlying value of transaction computed pursuant to Exchange Act Rule 0-11 (set forth the amount on which the filing fee is calculated and state how it was determined):

(4)

Proposed maximum aggregate value of transaction:

(5)

Total fee paid:

¨

Fee paid previously with preliminary materials.

¨

Check box if any part of the fee is offset as provided by Exchange Act Rule 0-11(a)(2) and identify the filing for which the offsetting fee was paid previously. Identify the previous filing by registration statement number, or the form or schedule and the date of its filing.

(1)

Amount Previously Paid:

(2)

Form, Schedule or Registration Statement No.:

(3)

Filing Party:

(4)

Date Filed:

Meeting Information            

Date:    May 22, 2012

      Time: 11:30 AM EDT

Location: Regency Hotel

                 New York, New York  10065

DIAMOND OFFSHORE DRILLING, INC.

15415 KATY FREEWAY

HOUSTON, TX 77094

You are receiving this communication because you hold shares in the above named company.

This is not a ballot. You cannot use this notice to vote these shares. This communication presents only an overview of the more complete proxy materials that are available to you on the Internet. You may view the proxy materials online at www.proxyvote.com or easily request a paper copy (see reverse side).

We encourage you to access and review all of the important information contained in the proxy materials before voting.

This notice also constitutes Notice of the 2012 Annual Meeting of Stockholders.

See the reverse side of this notice to obtain proxy materials and voting instructions.

Before You Vote  

1. Annual Report                 2. Notice and Proxy Statement

How to View Online:

Have the information that is printed in the box marked by the arrow  è   (located on the following page) and visit: www.proxyvote.com.

How to Request and Receive a PAPER or E-MAIL Copy:

If you want to receive a paper or e-mail copy of these documents, you must request one. There is NO charge for requesting a copy. Please choose one of the following methods to make your request:

                               1) BY INTERNET:         www.proxyvote.com

                               2) BY TELEPHONE:     1-800-579-1639

                               3) BY E-MAIL*:            sendmaterial@proxyvote.com

*  If requesting materials by e-mail, please send a blank e-mail with the information that is printed in the box marked by the arrow  è    (located on the following page) in the subject line.

Requests, instructions and other inquiries sent to this e-mail address will NOT be forwarded to your investment advisor. Please make the request as instructed above on or before May 8, 2012 to facilitate timely delivery.

How To Vote  

Vote In Person: Many stockholder meetings have attendance requirements including, but not limited to, the possession of an attendance ticket issued by the entity holding the meeting. Please check the meeting materials for any special requirements for meeting attendance. At the meeting, you will need to request a ballot to vote these shares.

Vote By Internet: To vote now by Internet, go to www.proxyvote.com. Have the information that is printed in the box marked by the arrow  è    available and follow the instructions.

Vote By Mail: You can vote by mail by requesting a paper copy of the materials, which will include a proxy card.

The Board of Directors recommends you vote

FOR Proposals 1, 2, 3 and 4: