Joint Filing Agreement

Exhibit 1

Joint Filing Agreement

The undersigned hereby agree that the Amendment No. 1 to the statement on Schedule 13D filed by the undersigned with respect to the Common Stock, Exchangeable Preferred Stock and the Warrant of Neurogen Corporation is, and any subsequent amendment thereto signed by each of the undersigned shall be, filed on behalf of each undersigned pursuant to and in accordance with the provisions of Rule 13d-1(k) under the Securities Exchange Act of 1934, as amended.

Dated:   April 14, 2008	WARBURG PINCUS PRIVATE EQUITY VIII, L.P.
	By:	Warburg Pincus Partners, LLC., its
		General Partner
	By:	Warburg Pincus & Co.,
		its Managing Member
	By:	/s/ Xxxxx X. Xxxxxxx
		Name: Xxxxx X. Xxxxxxx
		Title: Partner
Dated:   April 14, 2008	WARBURG PINCUS & CO.
	By:	/s/ Xxxxx X. Xxxxxxx
		Name: Xxxxx X. Xxxxxxx
		Title: Partner
Dated:   April 14, 2008	WARBURG PINCUS LLC
	By:	/s/ Xxxxx X. Xxxxxxx
		Name: Xxxxx X. Xxxxxxx
		Title: Member
Dated:   April 14, 2008	WARBURG PINCUS PARTNERS, LLC
	By:	Warburg Pincus & Co.,
		its Managing Member
	By:	/s/ Xxxxx X. Xxxxxxx
		Name: Xxxxx X. Xxxxxxx
		Title: Partner
Dated:   April 14, 2008

	By:		/s/ Xxxxx X. Xxxxxxx
			Name: Xxxxxxx X. Xxxx
			By: Xxxxx X. Xxxxxxx, Attorney-in-Fact(3)
Dated:   April 14, 2008
	By:	/s/ Xxxxx X. Xxxxxxx
		Name: Xxxxxx X. Xxxxx
		By: Xxxxx X. Xxxxxxx, Attorney-in-Fact(4)

(3) Power of Attorney given by Xx. Xxxx was previously filed with the SEC on March 2, 2006 as an exhibit to a Schedule 13D filed by Building Products, LLC with respect to Builders FirstSource, Inc.

(4) Power of Attorney given by Xx. Xxxxx was previously filed with the SEC on March 2, 2006 as an exhibit to a Schedule 13D filed by Building Products, LLC with respect to Builders FirstSource, Inc.