Exhibit 21.1 Subsidiaries of the Registrant Set forth below is a list of the significant subsidiaries of the Company as of July 31, 1996. Burnup & Sims Communication Services, Inc. Burnup & Sims ComTec, Inc. Burnup & Sims Network Designs Burnup & Sims of California, Inc. Burnup & Sims of Texas, Inc.* Burnup & Sims of the Carolinas, Inc. Burnup & Sims TelCom of Florida, Inc. Burnup & Sims TSI, Inc. Carolina Com-Tec, Inc.? Church & Tower, Inc.+ Church & Tower Fiber Tel, Inc. Church & Tower of Florida, Inc.+ Church & Tower of TN, Inc. Designed Traffic Installation Co., Inc.+ LatLink Corporation MasTec International, Inc. MasTec Teleport, Inc. Sistemas e Instalaciones de Telecomunicacion, S.A. # Utility Line Maintenance, Inc. @ The jurisdiction of incorporation for each of the subsidiaries is Delaware except the following: *Texas, +Florida, @ Georgia, #Spain, ?North Carolina. All operating subsidiaries of the Company are 100% owned, with the exception of MasTec Teleport, Inc. which is 80% owned.