In a questionnaire survey among surgical hospital departments in Denmark (1990), we assessed the attitudes and practices of use of postoperative thrombosis prophylaxis (TP). Replies were obtained from 92% of departments. Otological and odontological departments seldom used TP. Among departments performing major surgery a total of 88% used TP routinely (general surgery: 91%, orthopedic surgery: 94%, gynecology: 84%). 68% of these departments used TP according to written instructions. Indications for TP, and methods used, are in accordance with the literature, except for the use of TP in emergency surgery (routine in 36% of departments only), or for the continued use of aspirin for TP in 13% of departments.