Objective In order to evaluate the curative effects and mechanism of Ulinastatin on acute pancreatitis(AP). Methods 40 patients with AP were enrolled in this prospective study. They were comparable in dispearing time of symptoms and physical signs and laboratory data. Results The symptoms and physical signs of patients were significantly relieved in Ulinastatin group,and the labrotory data,such as the blood amylase and urine amylase recovered normal after five days with Ulinaststin. Conclution Ulinaststin has good clinical value in AP.