This is a study of two consecutive antithromboembolism regimens after total knee arthroplasty. In group 1, 131 patients were given aspirin prophylaxis alone (650 mg by mouth twice a day). In group 2, 123 patients were treated with aspirin, knee-high compression stockings, and intermittent knee-high pneumatic compression devices, which were started intraoperatively. The prevalence of deep vein thrombosis in group 1 was 15.9% (21 of 131 patients). One patient had a possible symptomatic nonfatal pulmonary embolism, and one patient had a symptomatic calf thrombus. Asymptomatic thrombi were detected in calf veins in 9 patients, popliteal vein in 6 patients, and femoral vein in 5 patients. In Group 2, the prevalence was 7.4% (9 of 123 patients). Asymptomatic thrombi were located in calf veins in 6 patients, popliteal vein in 1 patient, and femoral vein in 2 patients. There was a significant difference in the prevalence of deep vein thrombosis between the two groups. A history of previous thromboembolism was a significant risk factor for a new thrombus. The prevalence after bilateral one-stage knee arthroplasty was 24.3% for group 1 and 12.5% for group 2. Aspirin and knee-high intermittent pneumatic compression together are more effective than aspirin alone for prevention of deep vein thrombosis after primary and revision knee arthroplasty.