1 EX-21.1 SUBSIDIARIES EXHIBIT 21.1 PRESENT SUBSIDIARIES PERCENTAGE STATE OR OF VOTING JURISDICTION SECURITIES INCORPORATION OWNED ------------- ----- Teradyne ATE (Wuxi) Co., Ltd ....................... Peoples Republic of China 100% Teradyne Benelux, Inc. (Ltd.) ...................... Delaware 100% Teradyne Canada Limited ............................ Canada 100% Teradyne de Costa Rica S.A. ........................ Costa Rica 100% Teradyne GmbH ...................................... Germany 100% Teradyne Holdings Limited .......................... United Kingdom 100% Teradyne Limited ............................ United Kingdom 100% Teradyne Hong Kong, Ltd. ........................... Delaware 100% Teradyne International, Ltd. ....................... Barbados 100% Teradyne Ireland Limited ........................... Ireland 100% Teradyne Italia S.r.L .............................. Italy 100% Teradyne Japan, Ltd. ............................... Delaware 100% Teradyne K.K ................................ Japan 100% Teradyne Korea, Ltd. ............................... Delaware 100% Teradyne Leasing, Inc. ............................. Massachusetts 100% Teradyne Malaysia, Ltd. ............................ Delaware 100% Teradyne de Mexico, S.A. de C.V .................... Mexico 100% Teradyne Netherlands B.V ........................... Netherlands 100% Teradyne Netherlands, Ltd. ......................... Delaware 100% Teradyne Philippines Limited ....................... Delaware 100% Teradyne Realty, Inc. .............................. Massachusetts 100% Teradyne S.A.S. .................................... France 100% Teradyne Scandinavia, Inc. ......................... Delaware 100% Teradyne Singapore, Ltd. ........................... Delaware 100% Teradyne Spain, Inc. ............................... Delaware 100% Teradyne Taiwan, Ltd. .............................. Delaware 100% Teradyne Thailand Inc. ............................. Delaware 100% Alternative Delivery Systems Support, Inc. ......... North Carolina 100% Control Automation Inc. ............................ Delaware 100% Herco Technology Corp. ............................. California 100% Kinetrix, Inc. ..................................... Delaware 100% Megatest Corporation ............................... Delaware 100% Megatest H.K. Ltd. .......................... Hong Kong 100% Teradyne Philippines Ltd. ................... California 100% Perception Laminates, Inc. ......................... California 100% Softbridge, Inc..................................... Delaware 100% Zehntel Holdings, Inc. ............................. California 100% 1000 Washington, Inc. .............................. Massachusetts 100%