A survey was conducted of the attitudes and practices of New Zealand orthopaedic surgeons on the use of pharmacological thromboprophylaxis (PT) for patients undergoing major hip or knee surgery. A questionnaire was sent to all 106 consultant surgeons known to perform hip or knee surgery and a response rate of 89% was obtained. The results suggested that while almost all surgeons used PT at some time, only about one-third of elective surgery patients and just a few per cent of patients with neck of femur fracture (NOFF) receive PT. For about three-quarters of surgeons, heparin (usually low molecular weight) was the most frequently used PT. About half of the surgeons began prophylaxis pre-operatively and about half stopped it when the patients were mobile postoperatively. Previous venous thromboembolism was felt by almost all surgeons to be a very important indication for PT; gross obesity, prolonged pre-operative immobility and active malignancy were thought to be very important factors by approximately one-half of the surgeons. The presence of a major bleeding diathesis or active peptic ulcer was cited as a contraindication to PT by more than two-thirds of all surgeons. Fear of bleeding complications and the rarity of thromboembolic complications were cited as reasons for limited use of PT by about one-third of surgeons. The results suggest that most surgeons usually rely on non-pharmacological methods of thromboprophylaxis, particularly for NOFF patients.(ABSTRACT TRUNCATED AT 250 WORDS)