EXHIBIT 21 TELLABS, INC. AND SUBSIDIARIES SUBSIDIARIES OF THE REGISTRANT AS OF FEBRUARY 28, 1997 State or Other Jurisdiction of Name Incorporation Tellabs Operations, Inc. Delaware Tellabs Wireless, Inc. Delaware Tellabs Export, Inc. Delaware Telecommunications Laboratories, Inc. Illinois Tellabs International, Inc. Illinois Tellabs do Brasil Ltda. Brazil Tellabs Singapore Private Limited Singapore Tellabs Communications Canada Ltd. Ontario, Canada Tellabs (V.I.), Inc. U.S. Virgin Islands Tellabs H.K. Ltd. Hong Kong Tellabs N.Z. Limited New Zealand Tellabs Korea, Inc. Korea Tellabs Pty. Limited Australia Tellabs Holdings Ltd. Ireland Tellabs Ltd. Ireland Tellabs (Ireland) Ltd. Ireland Tellabs Research Ltd. Ireland Tellabs U.K. Ltd. United Kingdom Tellabs GmbH Germany Tellabs Southern Europe, S.A. Spain Tellabs Mexico, Inc. Delaware Tellabs de Mexico, S.A. de C.V. Mexico Tellabs Oy Finland Tellabs AB Sweden Tellabs SAS France Tellabs Pty. Ltd. South Africa Tellabs TG, Inc. Delaware Tellabs Transport Group Inc. Quebec, Canada