Technologies from three different medical disciplines are examined in an effort to demonstrate the potential benefit of epidemiologic surveillance of health care technologies. Tubal sterilization is a common surgical procedure done in a healthy population, and a surveillance mechanism is already in place. A surveillance system was instituted for insulin pump therapy in response to a perceived safety problem to demonstrate the need for postmarketing surveillance. Carotid endarterectomy has rapidly diffused into accepted practice in the United States despite the absence of evidence of efficacy and increasing controversy over its safety; no national surveillance is in place to monitor either its use or safety.