The purpose is to evaluate the efficacy of PGE1 during thrombolysis with Urokinase in experimental model. 21 rabbits averaging 2.5kg were anesthetized. Platelet-rich clots were made by modified Chandler loop method. A 3 Fr catheter was introduced into the abdominal aorta. The abdominal aorta was isolated and infrarenal branches was ligated. The aotric segment was temporarily occluded at both ends with ligatures and self-expandable stent. Two milliliters of clot was injected into the isolated segment. After 10 minutes, the proximal ligature was removed and distal stent preventing the caudal movement of the clot. Urokinase (4,000~200,000U) was administrated through the previously placed 3 Fr catheter with infusion pump. Aortogram was performed at 15 minutes interval and total infusion time was 120~150 minutes. And Urokinase (20,000~100,000U) and PGE1 20microgram were mixed and administrated. The degree of lysis of clots was evaluated with angiography in respect of changes of clot length. The results were as follow: Clot was started to form with Modified Chandlers method at 240 seconds and continued to 360-420 seconds. Thrombolysis with Urokinase was started at 20,000 U/hr and maintained the plateau at 100,000 U/hr and 200,000 U/hr with changes or clot density. Changes of clot size was started at 50,000 U/hr and increased to 200,000 U/hr. Changes of clot density and size were started at PGE1 20microgram with UK 20,000 U/hr and these changes were more prominent than with UK infusion only. In conclusion, changes of clot density and size with infusion of PGE1 and UK were more prominent than with infusion of UK only. So reduction of UK infusion can be expected with combined infusion of UK and PGE1.