In the retrospective study, we reviewed 228 patients with deep vein thrombosis (DVT) treated in our hospital from 1996 to 2007 to investigate the clinical features of DVT in patients with thrombophilia. Thrombophilia was diagnosed when either protein S (PS) antigen, protein C (PC) activity, or antithrombin III (ATIII) activity was decreased. Among 228 patients with DVT, 23 patients (10.1%) were found to have thrombophilia, consisting of 11 patients (4.8%) with PS deficiency, 7 patients (3.1%) with PC deficiency, and 6 patients (2.6%) with ATIII defi ciency. In the patients with thrombophilia, the age at the first appearance of DVT was significantly younger (39.9 ± 15.0 years old), and the incidence of the posotive family history of DVT (26.0%), of DVT with specific risk factors besides thrombphilia (69.6%), and repeated thrombosis (26.0%) were significantly higher than those in the patients without thrombophilia (p < 0.05). In the patients with thrombophilia, anticoagulant therapy with warfarin was had been discontinued when recurrence of thrombosis occurred, whereas the recurrence did not occurred as far as anticoagulant therapy continued. These results suggest that long-term anticoagulant therapy with warfarin is beneficial for DVT patients with thrombophilia to prevent repeated thrombosis.