AIM: To determine the timing of mortality after onset of severe acute pancreatitis (SAP) and the course of the disease in a large series of patients. METHODS: From July 1996 to June 2005, all patients diagnosed with acute pancreatitis at Chang Gung Memorial Hospital, Taipei, Taiwan were retrospectively studied. Three thousand two hundred and fifty episodes of acute pancreatitis were recorded in 2248 patients (1431 males and 817 females; median age, 55.6 years; range, 18-97 years). Mortality was divided into two groups: early death (≤ 14 d after admission), and late death (> 14 d after admission). The clinical features of patients in these two groups were compared. RESULTS: Although the overall mortality rate of acute pancreatitis was 3.8% (123/3250), mortality rate of SAP was as high as 16.3% (105/643). Of those 105 SAP mortalities, 44 (41.9%) deaths occurred within the first 14 d after admission and 61 (58.1%) occurred after14 d. Incidence of early death did not significantly differ from that of late death. The co-morbidities did not contribute to the timing of death. Early deaths mainly resulted from multiple organ failure. Late deaths were mainly caused by secondary complication of infected necrosis. Intra- abdominal bleeding significantly caused higher mortality in late death. CONCLUSION: Approximately half (42%) of SAP deaths occur within 14 d and most were due to multiple organ failure. The late deaths of SAP were mostly due to infected necrosis. AIM: To determine the timing of mortality after onset of severe acute pancreatitis (SAP) and the course of the disease in a large series of patients. METHODS: From July 1996 to June 2005, all patients diagnosed with acute pancreatitis at Chang Gung Memorial Hospital Three thousand two hundred and fifty episodes of acute pancreatitis were recorded in 2248 patients (1431 males and 817 females; median age, 55.6 years; range, 18-97 years). Mortality was divided into two groups : early death (≤ 14 d after admission), and late death (> 14 d after admission). The clinical features of patients in these two groups were compared. RESULTS: Although the overall mortality rate of an acute pancreatitis was 3.8% (123 / 3250), mortality rate of SAP was as high as 16.3% (105/643). Of those 105 SAP mortalities, 44 (41.9%) dieds occurred within the first 14 days after admission and 61 (58.1%) occurred after 14 days of early death did not significantly differ From that of late death. The co-morbidities did not contribute to the timing of death. Early deaths mainly caused from multiple timing failure. Early deaths were mainly caused by secondary complication of infected necrosis. CONCLUSION: Approximately half (42%) of SAP deaths occur within 14 d and most were due to multiple organ failure. The late deaths of SAP were mostly due to infected necrosis.