Exhibit 1

JOINT FILING AGREEMENT

In accordance with Rule 13d-1(k) under the Securities Exchange Act of 1934, as amended, the undersigned hereby agree to (i) the joint filing on behalf of each of them of a statement on Schedule 13D (including amendments thereto) with respect to the common stock of Pharsight Corporation and (ii) that this Joint Filing Agreement be included as an exhibit to such joint filing, provided that, as contemplated by Section 13d-1(k)(ii), no person shall be responsible for the completeness and accuracy of the information concerning the other persons making the filing unless such person knows or has reason to believe such information is inaccurate.

The Joint Filing Agreement may be executed in any number of counterparts all of which together shall constitute one and the same instrument.

Dated:  September 16, 2008	VECTOR CAPITAL III, L.P.
	By:	Vector Capital Partners III, L.L.C., is General Partner
	By:	/s/ Alexander R. Slusky
		Name:  Alexander R. Slusky
		Title:    Managing Member
	VECTOR CAPITAL PARTNERS III, L.L.C.
	By:	/s/ Alexander R. Slusky
		Name:   Alexander R. Slusky
		Title:     Managing Member
	ALEXANDER R. SLUSKY
		/s/ Alexander R. Slusky
		Alexander R. Slusky
	TRIPOS (DE), INC.
	By:	/s/ Dewey Chambers
		Name:   Dewey Chambers
		Title:     Treasurer
	TRIPOS INTERNATIONAL COOPERATIVE UA
	By:	/s/ Dewey Chambers
		Name:   Dewey Chambers
		Title:     Director
	TRIPOS (CAYMAN) LP
	By:	Tripos (Cayman) Ltd, is General Partner
	By:	/s/ Dewey Chambers
		Name:   Dewey Chambers
		Title:     Chief Financial Officer
	TRIPOS (CAYMAN) LTD
	By:	/s/ Dewey Chambers
		Name:   Dewey Chambers
		Title:     Chief Financial Officer