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                                                                   Exhibit 10.23
August 30, 2004

Lawrence E. Bloch
701 South Howard Avenue
Suite 106-389
Tampa, Florida  33606

Dear Larry:

I would like to formally offer you the position of Chief Financial Officer and
Chief Business Officer at NitroMed reporting to the President and Chief
Executive Officer.

The terms of this offer are as follows:

Responsibilities:          You will be responsible for all finance, business
                           development, information technology, facilities and
                           investor relations & public relations functions of
                           the Company.

Base Salary:               $265,000 per year paid in 24 equal payments to be
                           reviewed annually.

Stock:                     You will be offered an option to purchase 150,000
                           shares of common stock in the Company. The price at
                           which the stock closes on your start date will be
                           the exercise price of these options. You will be
                           offered an additional 60,000 options by year-end.
                           These options will vest over four years in equal
                           installments as long as you remain in the employ of
                           the Company. This four year vesting schedule will be
                           accelerated for these and all your options and any
                           other stock awards granted to you, if any, should
                           there be a change in control of the Company effective
                           immediately prior to the effectiveness of the
                           agreement for the change in control. For this
                           purpose, a change of control shall mean a transaction
                           (or a series of related transactions) resulting in
                           (1) a sale of all of the stock or substantially all
                           of the assets of the Company or (2) a corporate
                           merger, reorganization or consolidation of the
                           Company as a result of which the stockholders of the
                           Company prior to the transaction or transactions do
                           not own a majority of the stock of the successor or
                           surviving entity.

Performance Bonus:         You may be entitled to receive a bonus under the
                           NitroMed bonus plan, which is discretionary and based
                           on milestones to be determined and mutually agreed
                           upon by the Chief Executive Officer and you. You will
                           be entitled to receive a minimum guaranteed first
                           year bonus of 25% that will be prorated for the
                           months remaining between your date of hire and
                           December 31, 2004. Such bonus may be subject to an
                           upward adjustment in 2005, depending on performance.

Group Benefits:            You will receive comprehensive group health,
                           disability, accident and life insurance benefits or
                           such comparable benefits and protections the Company
                           is able to reasonably obtain from another plan. You
                           will be entitled to participate in and enjoy the
                           benefits of NitroMed's 401K retirement plan as well
                           as any other retirement and pension plan or plans

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                           if and when instituted by the Company for the benefit
                           of its employees generally.

Leave:                     You will be entitled to illness days consistent with
                           the Company's standard policy and 20 vacation days
                           per calendar year.

Relocation:                Subject to your continued employment the Company will
                           reimburse you for moving your household contents,
                           from your Florida residence. You will have 12 months
                           to exercise this relocation benefit. You will also be
                           entitled to six months of temporary housing
                           reimbursable at $3,000 per month. At your request,
                           the Company will pay directly all of the relocation
                           and temporary housing expenses for you.

Severance:                 You will be provided twelve months of your base
                           salary as a severance benefit if you are terminated
                           for reasons other than for "cause." Solely for this
                           purpose, the term "cause" shall mean any one of the
                           following intentional acts or omissions by you: (1)
                           embezzlement or other material misappropriation of
                           property of the Company, a breach of the Company's
                           assignment of invention, non-disclosure, and
                           non-compete agreements, or another willful act of
                           misconduct with the intent to harm the Company or its
                           employees, directors, shareholders, or agents; or
                           (2) the willful failure to perform your duties or
                           adhere to the policies of the Company that is not
                           corrected after you have been provided 30 days'
                           written notice by the Chief Executive Officer of the
                           Company to correct such failure.

Outside Activities:        You will be encouraged to serve on up to two outside
                           boards, provided such service does not interfere with
                           your NitroMed duties.

Agreements:                As a condition of employment, you will be required to
                           sign the Company's assignment of invention,
                           non-disclosure, and non-compete agreements.

The commencement date for this position is September 13, 2004. Please sign a
copy of this letter and return it as acceptance of this offer by September 2,
2004.

Larry, we look forward to working with you at NitroMed. It is my wish that this
position allows you to participate in the success of NitroMed and will both
enrich and enhance your career experience.

Sincerely,

/s/ Michael D. Loberg
---------------------
Michael D. Loberg

                              Agreed and Accepted:


                              /s/ Lawrence E. Bloch
                              ---------------------
                              Lawrence E. Bloch

                              Dated: August 30, 2004