Abstract: Objective To investigate the relationship between serum albumin variation within 24 hours of ICU admission and prognosis in critically ill patients with sever acute pancreatitis(SAP). Methods We retrospectively analyzed all the clinical data of the patients with SAP treated in ICU from Jul. 2005 to Jun. 2010. The patients were divided into two groups, survival group (n=131) and death group (n=108). Clinical and laboratory data, outcomes, and serum albumin within 24 hours after admission to ICU of those patients were evaluated respectively, and Logistic regression analysis was performed. Results Significant differences were existed between two groups (P<0.01) in average age, the score of acute physiology and chronic health evaluation Ⅱ (APACHE Ⅱ), Ranson criteria, the score of sequential organ failure assessment (SOFA), and albumin variation within 24 hours(Serum albumin descent degree and ratio in early stage). However, sex ratio, mean serum albumin concentration within 24 hours, and onset time did not have significant differences (P>0.05). The area under ROC curve for albumin variation within 24 hours were 0.728 and 0.742, the best cut-off values were 4.25 g/L(sensitivity 61.45%, specificity 81.67%) and 13.5%(sensitivity 62.65%, specificity 78.33%), respectively. Multiple logistic regression analysis showed that albumin variation within 24 hours was associated with death. Conclusion The albumin variation within 24 hours was the risk factors for poor prognosis of critically ill SAP in early stage.