XENOPORT, INC. CHANGE OF CONTROL AGREEMENT

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Exhibit 10.16

XENOPORT, INC.

CHANGE OF CONTROL AGREEMENT

This Change of Control Agreement (the "AGREEMENT") is made and entered

into by and between Pierre Tran (the "EXECUTIVE") and XenoPort, Inc. a Delaware

corporation (the "COMPANY"), effective as of July 15, 2004.

RECITALS

It is expected that the Company from time to time may consider the

possibility of an acquisition by another company or other change of control. The

Board of Directors of the Company (the "BOARD") recognizes that such

consideration can be a distraction to the Executive and can cause the Executive

to consider alternative employment opportunities. The Board has determined that

it is in the best interests of the Company and its stockholders to assure that

the Company will have the continued dedication and objectivity of the Executive,

notwithstanding the possibility, threat or occurrence of a Change of Control (as

defined below) of the Company.

The Board believes that it is in the best interests of the Company and its

stockholders to provide the Executive with an incentive to continue his

employment and to motivate the Executive to maximize the value of the Company

upon a Change of Control for the benefit of its stockholders.

Certain capitalized terms used in the Agreement are defined in Section 4

below.

The parties hereto agree as follows:

1. TERM OF AGREEMENT. This Agreement shall terminate upon the date that all

obligations of the parties hereto with respect to this Agreement have been

satisfied.

2. AT-WILL EMPLOYMENT. The Company and the Executive acknowledge that the

Executive's employment is and shall continue to be at-will. If the Executive's

employment terminates for any reason, including (without limitation) any

termination prior to a Change of Control, the Executive shall not be entitled to

any payments, benefits, damages, awards or compensation other than as provided

by this Agreement, or as may otherwise be available in accordance with the

Company's established written Executive plans or pursuant to other written

agreements with the Company.

3. TERMINATION FOLLOWING A CHANGE OF CONTROL.

(a) TERMINATION WITHOUT CAUSE OR VOLUNTARY TERMINATION FOR GOOD REASON. In

the event that a Change of Control (as defined below) of the Company occurs, and

during the period beginning on the closing date of the transaction giving rise

to such Change of Control and ending twelve (12) months after such closing date,

the Executive's employment with the Company (or the successor entity in such

Change of Control transaction) is either (1) terminated by the Company (or its

successor entity) without Cause (as defined below) or (2) terminated by the

Executive for Good Reason (as defined below), then the Executive shall be

entitled to receive Termination Benefits (as defined below).

1.

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(b) CONSTRUCTIVE TERMINATION. In the event that a Change of Control (as

defined below) of the Company occurs, and during the period beginning on the

closing date of the transaction giving rise to such Change of Control and ending

twelve (12) months after such closing date, the Executive's employment with the

Company (or the successor entity in such Change of Control transaction) is

Constructively Terminated (as defined below) by the Executive, then the

Executive shall be entitled to receive Termination Benefits (as defined below).

Notwithstanding the foregoing, the Executive shall not be entitled to the

Termination Benefits solely by reason of this Section 3(b) if the Executive

resigns his employment prior to the date six (6) months after the closing of the

transaction giving rise to such Change of Control.

4. DEFINITION OF TERMS. The following terms referred to in this Agreement shall

have the following meanings:

"CAUSE" shall mean either (i) any act of personal dishonesty taken by the

Executive in connection with his responsibilities as an Executive and intended

to result in substantial personal enrichment of the Executive, (ii) the

conviction of a felony, (iii) a willful act by the Executive which constitutes

gross misconduct and which is injurious to the Company, or (iv) following

delivery to the Executive of a written demand for performance from the Company

which describes the basis for the Company's belief that the Executive has not

substantially performed his duties, continued violations by the Executive of the

Executive's obligations to the Company which are demonstrably willful and

deliberate on the Executive's part.

"CHANGE OF CONTROL" means the completion by the Company of a

reorganization, merger, consolidation, in each case with respect to which

persons who were the stockholders of the Company immediately prior to such

reorganization, merger or consolidation would not immediately thereafter own

more than 50% of, respectively, the capital stock and the combined voting power

entitled to vote generally in the election of directors of the reorganized,

merged or consolidated corporation's then-outstanding voting securities, or of a

liquidation or