AIM: To investigate the clinical characteristics and prognostic factors of a consecutive series of patients with severe acute pancreatitis (SAP).METHODS: Clinical data of SAP patients admitted to our hospital from January 2003 to January 2004 were retrospectively reviewed. Collected data included the age, gender, etiology,length of hospitalization, APACHE Ⅱ score at admission,local and organ/systemic complications of the patients.RESULTS: Of the 268 acute pancreatitis patients, 94 developed SAP. The mean age of SAP patients was 52 years, the commonest etiology was cholelithiasis (45.7%), the mean length of hospitalization was 70 d, the mean score of APACHE Ⅱ was 7.7. Fifty-four percent of the patients developed necrosis, 25% abscess, 58% organ/systemic failure. A total of 23.4% (22/94) of the SAP patients died. Respiratory failure was the most common organ clysfunction (90.9%) in deceased SAP patients, followed by cardiovascular failure (86.4%),renal failure (50.0%). In the SAP patients, 90.9% (20/22)developed multiple organ/systemic failures. There were significant differences in age, length of hospitalization,APACHE Ⅱ score and incidences of respiratory failure, renal failure, cardiovascular failure and hematological failure between deceased SAP patients and survived SAP patients.By multivariate logistic regression analysis, independent prognostic factors for mortality were respiratory failure,cardiovascular failure and renal failure.CONCLUSION: SAP patients are characterized by advanced age, high APACHE Ⅱ score, organ failure and their death is mainly due to multiple organ/systemic failures. In patients with SAP, respiratory, cardiovascular and renal failures can predict the fatal outcome and more attention should be paid to their clinical evaluation.