1 Page 81 Exhibit 21 LIST OF SUBSIDIARIES Registrant - National Service Industries, Inc. Registrant owns all of the common stock of the following subsidiaries: State or Other Jurisdiction of Incorporation Subsidiary Principal Location or Organization Corisma Group, Inc. Atlanta, Georgia Georgia Lithonia Lighting Mexico, S.A. de C.V. Monterrey, Nuevo Leon Mexico Lithonia Lighting Products Co. of Arizona Conyers, Georgia Arizona Lithonia Lighting Products Co. of Georgia Conyers, Georgia Georgia Lithonia Lighting Products Co. of Nevada Conyers, Georgia Nevada National St. Louis Redevelopment Corporation Atlanta, Georgia Missouri NSI Holdings, Inc. Montreal, Quebec, Canada Canada NSI Insurance (Bermuda) Ltd. Hamilton, Bermuda Bermuda NSI Inversiones de Mexico, S.A. de C.V. Monterrey, Nuevo Leon Mexico NSI Leasing, Inc. Atlanta, Georgia Delaware Productos Lithonia Lighting de Mexico, S.A. de C.V. Monterrey, Nuevo Leon Mexico Selig Company of Puerto Rico, Inc. Atlanta, Georgia Puerto Rico South Insulation Co., Inc. Atlanta, Georgia Texas I.A. Enterprises, Inc. which owns the Santa Clara, California California stock of- Keplime B.V. Bergen op Zoom, Holland Netherlands Keplime Ltd. London, England United Kingdom ZEP Europe B.V. which owns the Bergen op Zoom, Holland Netherlands stock of- ZEP FRANCE Paris, France France Zep Industries S.A. Paris, France France Resolve S.A. Paris, France France Research Development Industries S.A. Paris, France France Chemical Continental Industries S.A.R.L. Paris, France France Zep Kem Italia S.r.l. Rome, Italy Italy Zep Cerfact S.r.l. Rome, Italy Italy Nobel Spain Madrid, Spain Spain ZEP Belgium S.A. Brussels, Belgium Belgium Research Development Industries S.A. Bern, Switzerland Switzerland Graham International B.V. Bergen op Zoom, Holland Netherlands Kem Europa B.V. Bergen op Zoom, Holland Netherlands Cerfact Europa B.V. Bergen op Zoom, Holland Netherlands Chemical Specialties B.V. Bergen op Zoom, Holland Netherlands NUS, Inc. which owns the stock of- Atlanta, Georgia Delaware NUS Florida, Inc. Atlanta, Georgia Florida Monroe Appearance Corp. Atlanta, Georgia North Carolina The consolidated financial statements include the accounts of all subsidiaries.