UNITED STATES
SECURITIES AND EXCHANGE COMMISSION

FORM 10-Q

(Mark One)

þ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d)
OF THE SECURITIES EXCHANGE ACT OF 1934

For the quarterly period ended March 31, 2005

OR

o TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d)
OF THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from ___________ to ___________

Commission File Number 001-15166

AMERUS GROUP CO.

699 Walnut Street
Des Moines, Iowa 50309-3948
(Address of principal executive offices)

Registrant’s telephone number, including area code (515) 362-3600

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 þ No o

Indicate by check mark whether the Registrant is an accelerated filer (as defined in Rule 12b-2 of the Exchange Act). Yes þ No o

The number of shares outstanding of each of the Registrant’s classes of common stock on May 2, 2005 was as follows:

Common Stock            39,172,030 shares

Exhibit index — Page 39
Page 1 of 41

INDEX

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SAFE HARBOR STATEMENT

     This Quarterly Report on Form 10-Q, including the Management’s Discussion and Analysis of Financial Condition and Results of Operations, contains statements which constitute forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, including statements relating to trends in operations and financial results and the business and the products of the Registrant and its subsidiaries, which include words such as “anticipate”, “believe”, “plan”, “estimate”, “expect”, “intend”, and other similar expressions. Forward-looking statements are made based upon management’s current expectations and beliefs concerning future developments and their potential effects on the Company. Such forward-looking statements are not guarantees of future performance. Factors that may cause our actual results to differ materially from those contemplated by these forward-looking statements include, among others, the following possibilities: (a) general economic conditions and other factors, including prevailing interest rate levels and stock and bond market performance, which may affect our ability to sell our products, the market value of our investments and the lapse rate and profitability of policies; (b) our ability to achieve anticipated levels of operational efficiencies and cost-saving initiatives and to meet cash requirements based upon projected liquidity sources; (c) customer response to new products, distribution channels and marketing initiatives; (d) mortality, morbidity, and other factors which may affect the profitability of our insurance products; (e) our ability to develop and maintain effective risk management policies and procedures and to maintain adequate reserves for future policy benefits and claims; (f) changes in the federal income tax and other federal laws, regulations, and interpretations, including federal regulatory measures that may significantly affect the insurance business including limitations on antitrust immunity, minimum solvency requirements, and changes to the tax advantages offered by life insurance and annuity products or programs with which they are used; (g) increasing competition in the sale of insurance and annuities and the recruitment of sales representatives; (h) regulatory changes, interpretations, initiatives or pronouncements, including those relating to the regulation of insurance companies and the regulation and sale of their products and the programs in which they are used; (i) our ratings and those of our subsidiaries by independent rating organizations which we believe are particularly important to the sale of our products; (j) the performance of our investment portfolios; (k) the impact of changes in standards of accounting; (l) our ability to integrate the business and operations of acquired entities; (m) expected protection products and accumulation products margins; (n) the impact of anticipated investment transactions; and (o) litigation or regulatory investigations or examinations.

     There can be no assurance that other factors not currently anticipated by us will not materially and adversely affect our results of operations. You are cautioned not to place undue reliance on any forward-looking statements made by us or on our behalf. Forward-looking statements speak only as of the date the statement was made. We undertake no obligation to update or revise any forward-looking statement.

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PART I — FINANCIAL INFORMATION

Item 1. Financial Statements

AMERUS GROUP CO.

See accompanying notes to consolidated financial statements.

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AMERUS GROUP CO.

See accompanying notes to consolidated financial statements.

5

AMERUS GROUP CO.

See accompanying notes to consolidated financial statements.

6

AMERUS GROUP CO.

See accompanying notes to consolidated financial statements.

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AMERUS GROUP CO.

See accompanying notes to consolidated financial statements.

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AMERUS GROUP CO.

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AMERUS GROUP CO.
CONSOLIDATED STATEMENTS OF CASH FLOWS — (Continued)
($ in thousands)

See accompanying notes to consolidated financial statements.

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AMERUS GROUP CO.

(1) CONSOLIDATION AND BASIS OF PRESENTATION

     The accompanying unaudited consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States (GAAP) for interim financial information and the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by GAAP for annual financial statements. In the opinion of management, all adjustments considered necessary for a fair presentation have been included. All adjustments were of a normal recurring nature, unless otherwise noted in the Notes to Consolidated Financial Statements. Operating results for the three months ended March 31, 2005 are not necessarily indicative of the results that may be expected for the year ending December 31, 2005. The consolidated balance sheet at December 31, 2004 has been derived from the audited financial statements at that date but does not include all of the information and footnotes required by GAAP for complete financial statements. For further information and for capitalized terms not defined in this Form 10-Q, refer to the consolidated financial statements and notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2004.

     The accompanying consolidated financial statements include the accounts and operations of the Company and its wholly-owned subsidiaries, principally AmerUs Life Insurance Company (ALIC), AmerUs Annuity Group Co. and its subsidiaries (collectively, AAG), AmerUs Capital Management Group, Inc. (ACM), and ILICO Holdings, Inc., the holding company of Indianapolis Life Insurance Company (ILIC) and its subsidiaries (collectively, ILICO). All significant intercompany transactions and balances have been eliminated in consolidation.

     The Company has certain stock-based employee compensation plans which are accounted for under the recognition and measurement principles of APB Opinion No. 25, “Accounting for Stock Issued to Employees,” and related interpretations. The plans are stock option plans for which no stock-based employee compensation cost is reflected in net income, as all options granted under those plans had an exercise price equal to the market value of the underlying common stock on the date of grant. The following table illustrates the effect on net income and earnings per share if the Company had applied the fair value recognition provisions of Statement of Financial Accounting Standards (SFAS) 123, “Accounting for Stock-Based Compensation,” to stock-based employee compensation:

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