Exhibit 21.1

Present Subsidiaries

Entity Name:	State or Jurisdiction Of Incorporation	Percentage of Voting Securities Owned
Teradyne Benelux, Inc. (Ltd.)	Delaware	100	%
Teradyne Canada Limited	Canada	100	%
Teradyne Connection Systems de Mexico, S.A. de C.V.	Mexico	100	%
Teradyne Connection Systems SDN BHD	Malaysia	100	%
Teradyne (Shanghai) Co., Ltd	Peoples Republic of China	100	%
Teradyne de Costa Rica S.A.	Costa Rica	100	%
Teradyne Diagnostic Solutions Ltd	United Kingdom	100	%
Teradyne Diagnostic Solutions Inc	Delaware	100	%*
Teradyne Diagnostic Solutions GmbH	Germany	100	%*
Teradyne Diagnostic Solutions S.A.S.	France	100	%*
Teradyne GmbH	Germany	100	%
Teradyne Holdings Limited	United Kingdom	100	%
Teradyne Limited	United Kingdom	100	%*
Teradyne Assembly Holdings Ltd.	United Kingdom	100	%
Teradyne Assembly Limited	United Kingdom	100	%*
Aegis Properties Limited	United Kingdom	100	%*
Teradyne Hong Kong, Ltd	Delaware	100	%
Teradyne International, Ltd	Barbados	100	%
Teradyne Ireland Limited	Ireland	100	%
Teradyne Italia SrL	Italy	100	%
Teradyne Japan, Ltd	Delaware	100	%
Teradyne KK	Japan	100	%*
Teradyne Singapore, Ltd.	Singapore	100	%
Teradyne Korea, Ltd	Delaware	100	%
Teradyne Malaysia, Ltd	Delaware	100	%
Teradyne de Mexico, SA de CV	Mexico	100	%
Teradyne Netherlands, Ltd	Delaware	100	%
Teradyne Philippines Limited	Delaware	100	%
Teradyne Realty, Inc	Massachusetts	100	%
Teradyne SAS	France	100	%
Teradyne Scandinavia, Inc	Delaware	100	%
Teradyne Singapore, Ltd	Delaware	100	%
Teradyne Spain, Inc	Delaware	100	%
Teradyne Taiwan, Ltd	Delaware	100	%
Teradyne Thailand Ltd	Delaware	100	%
GenRad, Inc.	Massachusetts	100	%
GenRad AB	Sweden	100	%*
GenRad SA	France	100	%*
GenRad Holdings Limited	United Kingdom	100	%*
GenRad Europe Limited	United Kingdom	100	%*
Mitron Europe Limited	United Kingdom	100	%*
Mastertech Automotive Ltd.	United Kingdom	100	%*
Motor Industry Services Ltd	United Kingdom	100	%*
Herco Technology Corp.	California	100	%
Perception Laminates, Inc.	California	100	%
TCMS, Inc.	Delaware	100	%
1000 Washington, Inc	Massachusetts	100	%

* Indirect subsidiaries whose voting securities are 100% controlled by Teradyne, Inc.