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ANNUAL REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

FOR THE FISCAL YEAR ENDED DECEMBER 31, 2004

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

FOR THE TRANSITION PERIOD FROM _______________ TO _______________

This amendment to Form 11-K on Form 11-K/A has been prepared solely to file the Plan's financial statements and schedules prepared in accordance with the financial reporting requirements of the Employee Retirement Income Security Act of 1974 ("ERISA"), as permitted by the Instructions to Form 11-K. No part of the Plan's Form 11-K for the fiscal year ended December 31, 2004 is affected by this amendment.

The following financial statements shall be furnished for the plan:

Items 1-3. The audited statement of financial condition and the audited statement of income and changes in plan equity are omitted pursuant to Item 4 of Form 11-K.

Item 4. Financial statements and schedules prepared in accordance with the financial reporting requirements of ERISA:

Page(s)

REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

3

FINANCIAL STATEMENTS AS OF AND FOR THE YEARS ENDED DECEMBER 31, 2004      AND 2003:

     Statements of Net Assets Available for Benefits

4

     Statements of Changes in Net Assets Available for Benefits

5

     Notes to Financial Statements

6-10

SUPPLEMENTAL SCHEDULE AS OF DECEMBER 31, 2004*:

     Form 5500, Schedule H, Part IV, Line 4i - Schedule of Assets (Held at End of Year)

11

SIGNATURES

12

INDEX TO EXHIBITS

13

2004

2003

ASSETS:

   Participant-directed investments, at fair value:

      Mutual funds

$    117,992,841

$      96,967,142

      Vanguard Retirement Savings Trust III

41,974,206

39,244,817

      Sun Life Financial Stock Fund

3,925,498

2,532,600

      Participant loans

2,793,123

2,720,549

      Cash

           235,406

         1,748,362

              Total investments

166,921,074

143,213,470

Contributions receivable

             -       

              58,918

NET ASSETS AVAILABLE FOR BENEFITS

$    166,921,074

$    143,272,388

See notes to financial statements.

2004

2003

ADDITIONS:

  Investment activity:

    Net appreciation in fair value of investments

$        8,858,849

$      17,274,360

    Interest

1,702,781

1,790,703

    Dividends

        3,767,574

        1,381,425

            Total investment activity

       14,329,204

     20,446,488

  Contributions:

    Employer

4,501,005

4,492,876

    Participants

13,395,158

12,639,723

    Employee rollovers

        2,041,618

           863,040

            Total contributions

      19,937,781

       17,995,639

            Total additions

      34,266,985

       38,442,127

DEDUCTIONS:

  Benefits paid to participants

       10,618,299

        6,534,827

            Total deductions

       10,618,299

         6,534,827

NET INCREASE

23,648,686

31,907,300

NET ASSETS AVAILABLE FOR BENEFITS:

  Beginning of year

     143,272,388

     111,365,088

  End of year

$     166,921,074

$     143,272,388

See notes to financial statements.

1.

DESCRIPTION OF THE PLAN

The following brief description of the Sun Life Assurance Company of Canada (U.S.) United States Employees' Sun Advantage Savings and Investment Plan (the "Plan") is provided for general information purposes only. Participants should refer to the Plan document for more complete information.

General - The Plan was originally established on April 1, 1986 by Sun Life Assurance Company of Canada (the "Corporation") for the benefit of its employees and the employees of its subsidiaries that elected to become participating employers under the Plan. The purpose of the Plan is to permit eligible employees of the Corporation and participating employers to defer and receive employer-matching contributions in order to provide funds for employees in the event of death, disability, unemployment and retirement. Any employee, 21 years or older, is eligible to become a participant in the Plan as soon as administratively feasible after his or her first day of employment. The Plan is subject to the provisions of the Employee Retirement Income Security Act of 1974 ("ERISA").

Effective January 1, 2002, the Corporation transferred sponsorship of the United States Employees' Sun Advantage Savings and Investment Plan to its wholly-owned subsidiary Sun Life Assurance Company of Canada (U.S.) (the "Company" or "Plan Sponsor").

Contributions - Once an employee becomes eligible to participate in the Plan, he or she may elect to become a participant by entering into a salary reduction agreement. The agreement provides that the participant agrees to accept a reduction in compensation in an amount equal to 1% to 60% of his or her compensation. During 2002, the Plan adopted Age 50 Catch Up Contributions as a result of the Economic Growth and Tax Relief Reconciliation Act of 2001. Contributions are subject to certain Internal Revenue Code ("IRC") limitations.

Participating employers contribute an amount equal to 50% of the first six percent of compensation that a participant contributes to the Plan.

Participant Accounts - Individual accounts are maintained for each plan participant. Each participant's account is credited with the participant's contribution, the participating employer's matching contribution, and allocations of Plan earnings, and charged with an allocation of plan losses and investment related expenses. Allocations are based on participant earnings or account balances, as defined in the plan document. The benefit to which a participant is entitled is the benefit that can be provided from the participant's vested account.

Investments - Participants direct the investment of their contributions into various investment options offered by the Plan. Participant selections of one or more of the investment options must be in multiples of 1%. Participating employer contributions are invested in accordance with participant investment allocations. The Plan currently offers several mutual funds, the Sun Life Financial Stock Fund, and a stable value fund as investment options for participants.

Vesting - Participants are vested immediately in their contributions plus actual earnings thereon. Vesting in the participating employer's contribution portion of their accounts is based on years of continuous service. A participant is 100 percent vested after five years of credited service. A participant is fully vested in his or her share of the participating employer matching contributions upon retirement at normal retirement age or older, disability, or death, regardless of the length of service.

Participant Loans - A participant may borrow up to 50% of his or her vested account balance with a maximum loan balance of $50,000. Repayment is effected through payroll deductions over a period of one to five years for non-mortgage loans and over a period of one to 15 years for mortgage loans. Loan repayments are credited against investments, as allocated in the participant's account. The loans are secured by the balance in the participant's account and bear interest at local prevailing rates at the time funds are borrowed. Interest rates range from 4% to 11%. Maturity dates range to September 30, 2019.

Payment of Benefits - The Plan provides for normal retirement benefits to be paid to participants who have reached the age of 65. If the participant's service with the participating employer terminates, other than by reason of retirement, the participant may elect to receive his or her distribution following his or her termination of employment. Distributions will be made in installments or in a lump sum, except if the participant's account balance is $5,000 or less, in which case payment will only be made in a lump sum.

Forfeitures - In the event that a participant terminates service prior to completing five years with the participating employer, the nonvested portion of his or her account will be forfeited. At December 31, 2004, forfeited nonvested accounts totaled $1,359,789. These accounts will be used to reduce future participating employer matching contributions. During the years ended December 31, 2004 and 2003, participating employer contributions were reduced by $0 and $66,025, respectively, from forfeited nonvested accounts.

2.

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

Basis of Accounting - The financial statements of the Plan are prepared in accordance with accounting principles generally accepted in the United States of America.

Use of Estimates - The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires the Plan Administrator to make estimates and assumptions that affect the reported amounts of net assets available for benefits and changes therein. Actual results could differ from those estimates. The Plan utilizes various investment instruments, including mutual funds, collective trusts, and stocks. Investment securities in general, are exposed to various risks, such as interest rate, credit, and overall market volatility. Due to the level of risk associated with certain investments, it is reasonably possible that changes in the values of investments will occur in the near term and that such changes could materially affect the amounts reported in the financial statements.

Investment Valuation and Income Recognition - The Plan's investments are stated at fair value based on quoted market prices. Shares of mutual funds are valued at the net asset value of shares held by the Plan at year-end. Investments in common collective trusts generally are valued at the redemption value established by the trustee, which generally is based on the fair value of the underlying assets. Participant loans are stated at cost plus accrued interest, which approximates fair value.

Management fees and operating expenses charged to the Plan for investments in mutual funds are deducted from income earned on a daily basis and are not separately reflected. Consequently, management fees and operating expenses are reflected as a reduction of investment return for such investments.

Payment of Benefits - Benefit payments to participants are recorded upon distribution.

Administrative Expenses - Administrative expenses of the Plan are paid by the Plan Sponsor.

Excess Contributions Payable - The Plan is required to return contributions received during the plan year in excess of IRC limits.

PLAN ADMINISTRATOR AND TRUSTEE

The U.S. Benefit Plans Committee (the "Committee") is the named Plan Administrator of the Plan. At December 31, 2004, the Committee consisted of six members: Janet V. Whitehouse, Claude Accum, Robert J. De Clercq, John T. Donnelly, Teresa A. Vellante Ham and Michael E. Shunney. State Street Bank and Trust Company is the named Trustee of the Sun Life Assurance Company of Canada (U.S.) United States Employees' Sun Advantage Savings and Investment Trust.

4.

FEDERAL INCOME TAX STATUS

The Plan obtained its latest determination letter dated October 29, 2002, in which the Internal Revenue Service stated that the Plan, as then designed, was in compliance with the applicable requirements of the IRC. The Plan has been amended since receiving the determination letter. However, the Committee believes that the Plan is currently designed and being operated in compliance with the applicable requirements of the IRC. Therefore, no provision for income taxes has been included in the Plan's financial statements.

5.

PLAN TERMINATION

Although it has not expressed any intention to do so, the Company has the right under the Plan to discontinue its contributions at any time and to terminate the Plan subject to the provisions set forth in ERISA. In the event that the Plan is terminated, participants would become 100 percent vested in their accounts.

6.

INVESTMENTS

The Plan's investments that represented 5% or more of the Plan's net assets available for benefits as of December 31 were as follows:

2004

2003

Mutual funds:

  MFS Growth Opportunities Fund

$16,220,854

$14,475,719

  Massachusetts Investors Trust

13,629,604

12,805,686

  MFS Total Return Fund

15,687,792

13,541,570

  Fidelity Blue Chip Growth Fund

20,618,743

19,230,652

  JP Morgan Capital Growth Fund

12,461,992

10,478,165

Collective trusts:

   Vanguard Retirement Savings Trust III

41,974,206

39,244,817

During 2004 and 2003, the Plan's investments (including gains and losses on investments bought and sold, as well as held, during the year) appreciated in value by $8,858,849 and $17,274,360, as follows:

Fund Name

Investment Type

2004

2003

Vanguard Retirement Savings Trust III

Stable Value

$       8,209 

$             - 

Vanguard Total Bond Index Admiral Shares

Fixed Income

(1,966)

(7,707)

MFS Government Securities Fund

Fixed Income

(21,891)

(175,092)

MFS High Income Fund

Fixed Income

67,590 

554,898 

MFS Total Return Fund

Balanced

862,627 

1,612,513 

T. Rowe Price Equity Income Fund

Equity

237,831 

126,356 

Vanguard 500 Index Fund Admiral Shares

Equity

584,715 

864,209 

Selected American Shares

Equity

25,465 

- 

MFS Massachusetts Investors Trust

Equity

1,304,745 

2,266,483 

Fidelity Blue Chip Growth Fund

Equity

1,072,700 

3,595,770 

MFS Growth Opportunities Fund

Equity

1,502,302 

3,185,073 

T. Rowe Price Mid-Cap Value Fund

Equity

14,208 

- 

J.P. Morgan Capital Growth Fund

Equity

335,021 

2,649,567 

Fidelity Low-Priced Stock Fund

Equity

1,032,139 

579,964 

Fidelity Small Cap Stock Fund

Equity

22,380 

- 

Fidelity Advisors Diversified International Fund

International Equity

48,173 

- 

T. Rowe Price International Stock Fund

International Equity

800,665 

1,315,036 

Sun Life Financial Stock

Company Stock

      963,936 

       707,290 

Total

$ 8,858,849 

$ 17,274,360 

RELATED-PARTY TRANSACTIONS

Certain Plan investments are managed by the Company's affiliates. At December 31, 2004 and 2003, the Plan held 117,668 and 101,223 shares, respectively, of common stock of Sun Life Financial Inc., an affiliate of the Plan Sponsor, with cost basis of $2,966,059 and $2,214,494, respectively. During the years ended December 31, 2004 and 2003, the Plan recorded dividend income of $73,790 and $55,778, respectively. These transactions qualified as permitted party-in-interest transactions.

SUN LIFE ASSURANCE COMPANY OF CANADA (U.S.)

UNITED STATES EMPLOYEES' SUN ADVANTAGE

SAVINGS AND INVESTMENT PLAN

FORM 5500, SCHEDULE H, PART IV, LINE 4i - SCHEDULE OF ASSETS (HELD AT END OF YEAR)

DECEMBER 31, 2004

(a)

(b) Identity of Issue,

(c) Description of Investment,

(d) Cost**

(e) Current

      Borrower, Lessor

      Including Collateral, Rate

       Value

      or Similar Party

      of Interest, Maturity Date,

      Par or Maturity Value

Vanguard

Retirement Savings Trust III -

    41,974,205.84 shares

$41,974,206

Mutual funds:

*

Massachusetts Financial Services

MFS Growth Opportunities Fund - 

    1,832,864.889  shares

16,220,854

MFS High Income Fund - 

    1,321,685.377 shares

5,299,958

MFS Government Securities Fund - 

    527,821.511 shares

5,125,147

MFS Total Return Fund - 

    980,486.993 shares

15,687,792

Massachusetts Investors Trust - 

    789,664.202 shares

13,629,604

Fidelity Investments

Fidelity Blue Chip Growth Fund - 

    494,335.744 shares 

20,618,743

Fidelity Low-Priced Stock Fund - 

    163,760.078 shares 

6,591,343

Fidelity Small Cap Value Fund -

    28,392.815 shares

515,614

Fidelity Advisor Diversified International

    32,422.489 shares

687,657

Vanguard

Vanguard S & P 500 Index Fund -

    67,230.467 shares 

7,505,609

Vanguard Total Market Bond Index Fund -

    187,128.528 shares 

1,921,810

JP Morgan

JP Morgan Capital Growth Fund -

    323,064.048 shares

12,461,992

T. Rowe Price

International Stock Fund - 

    541,648.800 shares

7,003,519

Equity Income Fund - 

    116,450.163 shares

3,096,409

Mid Cap Value Fund -

    51,054.281 shares

1,173,738

Select American Shares

Select American Shares -

    12,287.821 shares

         453,052

Total mutual funds

  117,992,841

*

Sun Life Financial

Sun Life Financial Inc. - Common Stock

    117,668.00 shares

      3,925,498

*

Plan participants

Loans to participants, secured by underlying

participant account balances, interest rates

From 4.00% to 11.00%, maturity

Dates through 2019

      2,793,123

Cash

         235,406

TOTAL INVESTMENTS

$166,921,074

Exhibit Number

Description

23

Consent of Independent Registered Public Accounting Firm