UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-K/A

(Amendment No. 1)

For the fiscal year ended December 31, 2008

or

For the transition period from              to             

Commission File Number: 2-64559

NATIONWIDE LIFE INSURANCE COMPANY

(Exact name of registrant as specified in its charter)

(614) 249-7111

(Registrant’s telephone number, including area code)

Securities registered pursuant to Section 12 (b) of the Act:

None

Securities registered pursuant to Section 12 (g) of the Act:

None

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act.

Yes  ¨    No  x

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act.

Yes  ¨    No  x

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.

Yes  x    No  ¨

Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S-K is not contained herein, and will not be contained, to the best of registrant’s knowledge, in definitive proxy or information statements incorporated by reference in Part III of this Form 10-K or any amendment to this Form 10-K.  x

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company. See the definitions of “large accelerated filer,” “accelerated filer” and “smaller reporting company” in Rule 12b-2 of the Exchange Act.

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act).

Yes  ¨    No  x

No established published trading market exists for the registrant’s common stock, par value $1.00 per share. As of February 25, 2008, 3,814,779 shares of the registrant’s common stock were outstanding, all of which are held by Nationwide Financial Services, Inc.

The Registrant meets the conditions set forth in General Instruction I(1)(a) and (b) of Form 10-K and is therefore filing this Form with the reduced disclosure format.

Explanatory Note

This Amendment No. 1 amends Nationwide Life Insurance Company’s (the “Company”) Annual Report on Form 10-K for the fiscal year ended December 31, 2008, which was filed with the Securities and Exchange Commission on March 2, 2009 (the “Original Filing”). The Company is filing this Amendment No. 1 solely for the purpose of amending Part IV, Item 15, Exhibits 31.1 and 31.2 to include language in paragraph 4 referring to internal control over financial reporting. No other changes have been made to the Original Filing.

SIGNATURES

Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

Pursuant to the requirements of the Securities Exchange Act of 1934, this report has been signed below by the following persons on behalf of the registrant and in the capacities and on the dates indicated.

Exhibit Index