To determine intraoperative factors which may influence deep vein thrombosis rate, we studied surgeries performed by one surgeon on 441 consecutive patients undergoing primary total hip arthroplasty under epidural anesthesia. Operative limb venography was performed on the fourth or fifth postoperative day in 381 patients, who received 650 mg of aspirin daily as the only postoperative thromboprophylaxis. Of 381 (15%) patients, 58 had a positive venogram; 13 (3%) had proximal thrombi. Of 178 patients (9.5%) with surgery lasting less than 70 min, 17 developed deep vein thrombosis whereas 41 of 203 patients (20.3%) with surgery lasting more than 70 min developed deep vein thrombosis (P < 0.05). Corresponding proximal deep vein thrombosis rates increased from 1.7% to 4.9%. Deep vein thrombosis was observed in 12.5% of patients receiving intravenous low-dose epinephrine, 10.3% receiving intravenous sodium nitroprusside, 14.5% receiving both low-dose epinephrine and sodium nitroprusside concurrently, and 25% receiving intravenous fluid alone. Proximal deep vein thrombosis rates were 2.4%, 0%, 1.45%, and 9.3% in these groups, respectively. These data suggest that the intraoperative management of both surgery and anesthesia influence rates of deep vein thrombosis following total hip arthroplasty.