Recent diagnostic and therapeutic progress for severe acute pancreatitis(SAP)remarkably decreased the casemortality rate.To further decrease the mortality rate of SAP,it is important to precisely evaluate the severity at an early stage,and initiate appropriate treatment as early as possible.Research Committee of Intractable Diseases of the Pancreas in Japan developed simpler criteria combining routinely available data with clinical signs.Severity can be evaluated by laboratory examinations or by clinical signs,reducing the defect values of the severity factors.Moreover,the severity criteria considered laboratory/clinical severity scores and contrastenhanced computed tomography(CE-CT)findings as independent risk factors.Thus,CE-CT scans are not necessarily required to evaluate the severity of acute pancreatitis.There was no fatal case in mild AP diagnosed by the CE-CT severity score,whereas case-mortality rate in those with SAP was 14.8%.Case-mortality of SAP that fulfilled both the laboratory/clinical and the CE-CT severity criteria was 30.8%.It is recommended,therefore,to perform CE-CT examination to clarify the prognosis in those patients who were diagnosed as SAP by laboratory/clinical severity criteria.Because the mortality rate of these patients with SAP is high,such patients should be transferred to advanced medical units. Recent diagnostic and therapeutic progress for severe acute pancreatitis (SAP) remarkably decreased the case rate. T o further decrease the mortality rate of SAP, it is important to precisely evaluate the severity at an early stage, and so appropriate treatment as early as possible. Research Committee of Intractable Diseases of the Pancreas in Japan developed simpler criteria combining routinely available data with clinical signs. Severity can be evaluated by laboratory examinations or by clinical signs, reducing the defect values ​​of the severity factors. More over, the severity criteria deemed laboratory / clinical severity scores and contrastenhanced computed tomography (CE-CT) findings as independent risk factors. Thus, CE-CT scans are not necessarily required to evaluate the severity of acute pancreatitis. There was no fatal case in mild AP diagnosed by the CE-CT severity score, case case-mortality rate in those with SAP was 14.8%. Case-mortality of SAP that fulfilled both the lab It is recommended, therefore, to perform CE-CT examination to clarify the prognosis in those patients who were diagnosed as SAP by laboratory / clinical severity criteria. Disease is of 30.8%. these patients with SAP is high, such patients should be transferred to advanced medical units.