EXHIBIT 5

2200 Wells Fargo Center, 90 South Seventh Street

Minneapolis, Minnesota 55402-3901

TELEPHONE 612.766.7000

FACSIMILE 612.766.1600

www.faegre.com

April 9, 2009

FSI International, Inc.
3455 Lyman Boulevard
Chaska, Minnesota 55318

Ladies and Gentlemen:

     In connection with the Registration Statement on Form S-8 under the Securities Act of 1933, as amended (the “Registration Statement”), relating to the offering of up to an additional 500,000 shares of common stock, without par value (the “Shares”), of FSI International, Inc., a Minnesota corporation (the “Company”), pursuant to the Company’s 2008 Omnibus Stock Plan, as amended, and up to an additional 1,000,000 Shares pursuant to the Company’s Employees Stock Purchase Plan, as amended and restated (collectively, the “Plans”), we have examined such corporate records and other documents, including the Registration Statement, and have reviewed such matters of law as we have deemed relevant hereto, and, based upon such examination and review, it is our opinion that all necessary corporate action on the part of the Company has been taken to authorize the issuance and sale of the Shares and that, when issued and sold as contemplated by the Plans and the Registration Statement, the Shares will be legally issued, fully paid, and nonassessable under the current laws of the State of Minnesota.

     We are admitted to the practice of law in the State of Minnesota and the foregoing opinions are limited to the laws of that state and the federal laws of the United States of America.

     We consent to the filing of this opinion as an exhibit to the Registration Statement.

Very truly yours, FAEGRE & BENSON LLP
By:	/s/ Douglas P. Long
	Douglas P. Long