MIDAMERICAN ENERGY COMPANY and THE BANK OF NEW YORK TRUST COMPANY, N.A., as Trustee ________________ 5.65% Senior Notes due 2012 5.95% Senior Notes due 2017 ________________ Second Supplemental Indenture ________________ Dated as of June 29, 2007

SECOND SUPPLEMENTAL INDENTURE, dated as of June 29, 2007 (herein called the “Second Supplemental Indenture”), between MIDAMERICAN ENERGY COMPANY, a corporation duly organized and existing under the laws of the State of Iowa (herein called the “Company”), and THE BANK OF NEW YORK TRUST COMPANY, N.A., a New York banking association duly organized and existing under the laws of the United States of America, as Trustee (herein called the “Trustee”), under the Original Indenture referred to below.

W I T N E S S E T H :

WHEREAS, the Company has heretofore executed and delivered to the Trustee an indenture dated as of October 1, 2006 (herein called the “Original Indenture”), to provide for the issuance from time to time of its unsubordinated debentures, notes or other evidences of indebtedness, the form and terms of which are to be established as set forth in Sections 2.01 and 3.01 of the Original Indenture;

WHEREAS, the Company has heretofore executed and delivered to the Trustee a first supplemental indenture dated as of October 6, 2006, as amended (herein called the “First Supplemental Indenture”), to provide for the issuance of up to an aggregate principal amount of three hundred fifty million dollars ($350,000,000) of its 5.800% Notes due 2036 under the Original Indenture;

WHEREAS, Section 9.01 of the Original Indenture provides, among other things, that the Company and the Trustee may enter into indentures supplemental to the Original Indenture for, among other things, (i) the purpose of establishing the form and terms of the Securities (as defined in the Original Indenture) of any series as permitted by Sections 2.01 and 3.01 of the Original Indenture, and (ii) to add to the covenants of the Company for the benefit of the Holders of all or any series of Securities (as defined in the Original Indenture);

WHEREAS, the Company desires to create two series of its unsecured securities, one series of its securities in an aggregate principal amount of Two Hundred Fifty Million Dollars ($250,000,000) to be designated the “5.95% Senior Notes due 2017” and one series of its securities in an aggregate principal amount of Four Hundred Million Dollars ($400,000,000) to be designated the “5.65% Senior Notes due 2012” (together, the “Securities”), and all action on the part of the Company necessary to authorize the issuance of the Securities under the Original Indenture and this Second Supplemental Indenture has been duly taken;

WHEREAS, the Company and the Trustee desire to make certain amendments to the Original Indenture in conformance with the requirements described above; and

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