Exhibit 5.1

ASML

ASML Holding N.V.

De Run 6501

5504 DR Veldhoven

PO Box 324

5500 AH Veldhoven

The Netherlands

Phone +31 40 268 6762

Fax +31 40 268 4888

remco.van.der.veer@asml.com

www.asml.com

Trade Register 17085815

Eindhoven, The Netherlands

United States Securities and Exchange
Commission
450 Fifth Street, N.W.
Washington, D.C. 20549
United States of America

Date	April 11, 2007
Reference	RV/1_3_2_18
Subject	Form S-8

Ladies and Gentlemen:

     I refer to the Registration Statement on Form S-8 (the “Registration Statement”) of ASML Holding N.V., a Netherlands corporation (the “Company”) under the Securities Act of 1933 (the “Securities Act”). The Registration Statement relates to up to 936,461 ordinary shares, nominal value of €0.02 per share, of ASML Holding N.V. (the “Ordinary Shares”), issuable under the Brion Technologies, Inc., 2002 Stock Option Plan (as amended on March 25, 2005; March 24, 2006; and November 17, 2006) (the “Plan”).

     I have examined and am familiar with (i) the Company’s Articles of Association, as amended and (ii) the corporate proceedings relating to the Registration Statement. Upon the basis of the foregoing, and having satisfied myself as to such other matters of law and fact as I consider relevant for the purposes of this opinion, I advise you that, in my opinion, upon issuance in accordance with the terms and conditions of the applicable Plan, the Ordinary Shares will have been legally issued, fully paid and non-assessable.

United States Securities and Exchange Commission
April 11, 2007
Page 2

     I express no opinion herein, on or with respect to, any law other than the laws of The Netherlands and I express no opinion on, or with respect to, the laws of the United States, any state thereof or any other laws, statutes, regulations or ordinances.

     I hereby consent to the filing of this opinion as an exhibit to the Registration Statement and any reference to me therein. In giving such consent, I do not hereby admit that I am in the category of persons whose consent is required under Section 7 of the Securities Act or the rules and regulations of the Commission.

Very truly yours
 

/s/ Robert F. Roelofs 

Robert F. Roelofs 

General Counsel