Page 77 Exhibit 21 LIST OF SUBSIDIARIES Registrant - National Service Industries, Inc. State or Other Jurisdiction of Incorporation Subsidiary Principal Location or Organization Lithonia Lighting Mexico, S.A. de C.V. Monterrey, Nuevo Leon Mexico Lithonia Lighting Servicios, S.A. de C.V. Monterrey, Nuevo Leon Mexico National Service Industries, Inc. Atlanta, Georgia Georgia North Bros., Inc. Atlanta, Georgia Delaware NSI Enterprises, Inc. which owns the stock of- Atlanta, Georgia Georgia CORISMA Group, Inc. Atlanta, Georgia Georgia Keplime B.V. Bergen op Zoom, Holland Netherlands NSI Holdings, Inc. Montreal,Quebec,Canada Canada NSI Insurance (Bermuda) Ltd. Hamilton, Bermuda Bermuda 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 ZEP Europe B.V. which owns the stock of- Bergen op Zoom, Holland Netherlands ZEP FRANCE Nogent-le-Roi, France France Zep Industries S.A. Nogent-le-Roi, France France Resolve S.A. Nogent-le-Roi, France France Research Development Industries S.A. Nogent-le-Roi, France France Chemical Continental Industries S.A.R.L Nogent-le-Roi, France France Zep Italia S.r.l. Aprilia, Italy Italy ZEP Belgium S.A. Brussels, Belgium Belgium Zep S.A. Bern, Switzerland Switzerland Graham International B.V. Bergen op Zoom, Holland Netherlands Kem Europa B.V. Bergen op Zoom, Holland Netherlands Zep Manufacturing B.V. Bergen op Zoom, Holland Netherlands Chemical Specialties B.V. Bergen op Zoom, Holland Netherlands Zep Manufacturing Company Santa Clara, California Delaware The consolidated financial statements include the accounts of all subsidiaries.