Pulmonary thromboembolism (PTE) is a life-threatening disease which always presents in patients with deep vein thrombosis (DVT). There are few statements in guidelines regarding indications for anticoagulation based on the location of DVT. We investigated whether the relative risk of PTE depends on thrombus location and bleeding complications with anticoagulation therapy. Between January 1 and July 10, 2007, 461 patients underwent lower extremity venous ultrasound studies, and 129 patients were diagnosed as DVT (60 males, 66.9 ± 13.3 years). We retrospectively studied the incidence of PTE and bleeding complications associated with anticoagulation therapy. Average follow-up period was 536 ± 324 days. Above and below knee thrombosis was present in 60 and 69 patients, respectively. Warfarin was administered in 60 patients. Nine patients developed PTE. Multivariate analysis showed the absence of anticoagulation therapy and location of DVT (above knee) to be significantly correlated with onset of PTE (anticoagulation; P < 0.01, location; P = 0.02). However, the incidence of bleeding was not significantly different between above knee and below knee vein thrombosis (P = 0.72). In conclusion, below knee vein thrombosis carries a relatively low risk of PTE, but the incidence of bleeding complications does not depend on thrombosis location. This suggests that the indication of anticoagulation therapy should be based on DVT location.