ANADARKO PETROLEUM CORPORATION 8.700% Senior Notes due 2019

Exhibit 4.3

[Form of Face of Note of Sixth Series]

     [ Insert if Global Security — THIS SECURITY IS A GLOBAL SECURITY WITHIN THE MEANING OF THE INDENTURE HEREINAFTER REFERRED TO AND IS REGISTERED IN THE NAME OF A DEPOSITARY OR A NOMINEE THEREOF. THIS SECURITY MAY NOT BE EXCHANGED IN WHOLE OR IN PART FOR A SECURITY REGISTERED, AND NO TRANSFER OF THIS SECURITY IN WHOLE OR IN PART MAY BE REGISTERED, IN THE NAME OF ANY PERSON OTHER THAN SUCH DEPOSITARY OR A NOMINEE THEREOF, EXCEPT IN THE LIMITED CIRCUMSTANCES DESCRIBED IN THE INDENTURE.]

ANADARKO PETROLEUM CORPORATION

8.700% Senior Notes due 2019

     ANADARKO PETROLEUM CORPORATION, a corporation duly organized and existing under the laws of the State of Delaware (herein called the “ Company ”, which term includes any successor Person under the Indenture hereinafter referred to), for value received, hereby promises to pay to .................................... , or registered assigns, the principal sum of ................................. Dollars on March 15, 2019, and to pay interest thereon from March 5, 2009 or from the most recent Interest Payment Date to which interest has been paid or duly provided for, semi-annually on March 15 and September 15 in each year, commencing September 15, 2009, and at the Maturity thereof, at the rate of 8.700% per annum, until the principal hereof is paid or made available for payment. The interest so payable, and punctually paid or duly provided for, on any Interest Payment Date will, as provided in such Indenture, be paid to the Person in whose name this Security (or one or more Predecessor Securities) is registered at the close of business on the Regular Record Date for such interest, which shall be the March 1 or September 1 (whether or not a Business Day), as the case may be, next preceding such Interest Payment Date. Any such interest so payable, but not punctually paid or duly provided for, will forthwith cease to be payable to the Holder on such Regular Record Date and may either be paid to the Person in whose name this Security (or one or more Predecessor Securities) is registered at the close of business on a Special Record Date for the payment of such Defaulted Interest to be fixed by the Trustee, notice whereof shall be given to Holders of Securities of this series not less than 10 days prior to such Special Record Date, or be paid in any other lawful manner not inconsistent with the requirements of any securities exchange on which this Security may be listed, and upon such notice as may be required by such exchange, all as more fully provided in said Indenture.

     Payment of the principal of (and premium, if any) and interest on this Security will be made at the office or agency of the Company maintained for that purpose in New York, New York, in such coin or currency of the United States of America as at the time of payment is legal

tender for payment of public and private debts, against surrender of this Security in the case of any payment due at the Maturity of the principal thereof or any payment of interest becomes payable on a day other than an Interest Payment Date; provided , however , that if this Security is not a Global Security, (i) payment of interest on an Interest Payment Date will be made by check mailed to the address of the Person entitled thereto as such address shall appear in the Security Register; and all other payments will be made by check against surrender of this Security; (ii) all payments by check will be made in next-day funds ( i.e. , funds that become available on the day after the check is cashed); and (iii) notwithstanding clauses (i) and (ii) above, with respect to any payment of any amount due on this Security, if this Security is in a denomination of at least $1,000,000 and the Holder hereof at the time of surrender hereof or, in the case of any payment of interest on any Interest Payment Date, the Holder thereof on the related Regular Record Date delivers a written request to the Paying Agent to make such payment by wire transfer at least five Business Days before the date such payment becomes due, together with appropriate wire transfer instructions specifying an account at a bank in New York, New York, the Company shall make such payment by wire transfer of immediately available funds to such account at such bank in New York City, any such wire instructions, once properly given by a Holder as to this Security, remaining in effect as to such Holder and this Security unless and until new instructions are given in the manner described above; and provided further , that notwithstanding anything in the foregoing to the contrary, if this Security is a Global Security, payment shall be made pursuant to the Applicable Procedures of the Depositary as permitted in said Indenture.

     Reference is hereby made to the further provisions of this Security set forth on the reverse hereof, which further provisions shall for all purposes have the same effect as if set forth at this place.

     Unless the certificate of authentication hereon has been executed by the Trustee referred to on the reverse hereof by manual signature, this Security shall not be entitled to any benefit under the Indenture or be valid or obligatory for any purpose.

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     IN WITNESS WHEREOF, the Company has caused this instrument to be duly executed under its corporate seal.

This is one of the Securities of the series designated herein and referred to in the within-mentioned Indenture.

[Form of Reverse of Note of Sixth Series]

     This Security is one of a duly authorized issue of senior securities of the Company (herein called the “ Securities ”), issued and to be issued in one or more series under an Indenture, dated as of September 19, 2006 (herein called the “ Indenture ”, which term shall have the meaning assigned to it in such instrument), between the Company and The Bank of New York Mellon Trust Company, N.A. (formerly, The Bank of New York Trust Company, N.A.), as Trustee (herein called the “ Trustee &rdqu