PURPOSE: To determine whether the addition of heparin to urokinase during dialysis graft thrombolysis can lower urokinase dose and shorten procedure time. PATIENTS AND METHODS: Patients who underwent dialysis graft thrombolysis during an 18-month period were studied retrospectively, Twenty patients were treated with urokinase alone, and 19 patients were treated with urokinase and heparin, Thrombolysis was performed in the angiography suite by using a crossed-catheter technique, Urokinase was administered directly into the thrombus, In patients receiving heparin, 5,000 IU was added directly to the initial urokinase solution. RESULTS: In patients who received urokinase alone, an average of 750,000 U of urokinase was used, and the average procedure time was 2 hours 42 minutes, When heparin was added, an average of 435,000 U of urokinase was used, and the average procedure time was 2 hours. CONCLUSION: The addition of heparin to urokinase can decrease both urokinase dose and thrombolysis time in the recanalization of dialysis grafts.