To evaluate conservative treatment for acute deep vein thrombosis (DVT) of lower extremities, 56 limbs of 53 patients (29 men and 24 women, age ranging 20 to 77 years, mean age of 50.1 years) were reviewed. Only three patients underwent thrombectomy of restricted iliac venous regions by Fogarty catheter within 24 hours of the onset and their symptoms were relieved immediately after operation with good follow-up condition. Forty-five limbs were treated conservatively. Among 45 limbs, 15 limbs were treated within 7 days of symptom's onset using heparin and urokinase for 6-10 days followed by oral anticoagulant. Forty-seven percent of the patients were freed from their symptoms within one year. However 30 limbs received conservative therapy after 7 days of the onset showed 23% recovery from their symptoms within one year and in extensive thrombosis recovery was only 14%. We concluded that conservative treatment for DVT was effective if it was started within 7 days of the onset, and thrombectomy of ilio-femoral regions might be more effective than conservative treatment under the same condition.