UNLABELLED: We used aspirin and mechanical calf pneumatic compression for thromboembolism prophylaxis in 856 consecutive primary and revision total knee arthroplasties. Regional anesthesia was used in 97% of the procedures. Duplex ultrasonography was performed before discharge. We advised patients with calf thrombi to continue aspirin and have repeat duplex scans in 7 to 10 days. Patients with popliteal or femoral thrombi were given low-molecular-weight heparin and warfarin for 6 weeks. Using this protocol, the 90-day mortality rate was 0.14%. There was one fatal myocardial infarction. Three patients developed symptomatic nonfatal pulmonary embolisms, two occurring early and one late. Deep vein thrombosis occurred in 56 patients (9.3%). Only nine patients (1.5%) had symptomatic thrombosis, with four ipsilateral calf and five ipsilateral proximal thrombi. The data confirm the efficacy of a multimodal protocol with calf mechanical prophylaxis for almost all patients undergoing primary or revision total knee arthroplasty. LEVEL OF EVIDENCE: Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.