1 Page 46 Exhibit 21 LIST OF SUBSIDIARIES Registrant - National Service Industries, Inc. Registrant owns, directly or indirectly, all of the common stock of the following subsidiaries: State or Other Jurisdiction of Incorporation Subsidiary Principal Location or Organization - ----------------------------------------- ----------------------- ---------------- Chemical Continental Industries S.A.R.L. Nogent-le-Roi, France France Chemical Specialties B.V. Bergen op Zoom, Holland Netherlands Graham International B.V. Bergen op Zoom, Holland Netherlands Kem Europa B.V. Bergen op Zoom, Holland Netherlands Keplime B.V. Bergen op Zoom, Holland Netherlands 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 NSI Enterprises, Inc. Atlanta, Georgia California 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 Research Development Industries S.A. Nogent-le-Roi, France France Resolve S.A. Nogent-le-Roi, France France Selig Company of Puerto Rico, Inc. Atlanta, Georgia Puerto Rico ZEP Belgium S.A. Brussels, Belgium Belgium ZEP Europe B.V. Bergen op Zoom, Holland Netherlands ZEP FRANCE Nogent-le-Roi, France France Zep Industries S.A. Nogent-le-Roi, France France Zep Italia S.r.l. Aprilia, Italy Italy Zep Manufacturing B.V. Bergen op Zoom, Holland Netherlands Zep Manufacturing Company Santa Clara, California Delaware Zep S.A. Bern, Switzerland Switzerland The consolidated financial statements include the accounts of all subsidiaries.