Patients undergoing surgery for carcinoma of the breast are thought to be at lower risk of developing thromboembolic complications than those with abdominal malignancies and the role of the thromboprophylaxis is unproven. To determine current thromboprophylaxis practice a questionnaire was sent to 184 consultant surgeons thought to be involved in breast cancer surgery, of whom 137 responded (74%). Eleven surgeons no longer dealt with breast cancer patients. Of the remaining 126, thromboprophylaxis was given routinely by 88 (69.8%), with the commonest regimens being subcutaneous heparin only (n=43) and heparin combined with compression stockings (n=20). Patients with breast cancer were regarded as being at high risk of thromboembolic complications by 65 clinicians in this group (73.7%). Thirty-eight consultants did not use thromboprophylaxis routinely, the most commonly stated reasons were low/no risk of DVT (n=24), because of early postoperative mobilization (n=20) and increased risk of bleeding complications (n=15). Twenty clinicians reported a total of 22 deep venous thromboses and two pulmonary emboli affecting patients under their care who had surgery for breast cancer during the preceding year. Almost 70% of surgeons routinely employ thromboprophylaxis in patients undergoing breast cancer surgery but practice varies widely.