Background: The bedside index for severity in acute pancreatitis (BISAP), a newer prognostic scoring system, has been proposed as a simple and clinically oriented severity scoring system for early identification of patients with acute pancreatitis. This study evaluates the efficacy of BISAP score to predict the severity of organ failure in patients of acute pancretitis and its correlation with Marshall score.Methods: The clinical, laboratory and radiological data for all patients admitted with a diagnosis of acute pancreatitis conducted at tertiary hospital of Armed Forces over a two-year period, was prospectively collected for this study. BISAP score was calculated within 24hrs of presentation. Markers of severity were the development of organ failure and presence of pancreatic necrosis. Outcome at 28 days (viz. recovery, organ failure and mortality) was studied for each patient. BISAP score computed at 24h was correlated with the above and its efficacy to predict the severity of organ failure in Acute Pancreatitis, was assessed.Results: Out of 50 patients in the study group, 41 were male and 9 were female with the mean (±SD) age 43.74±16.85 years. Majority of the study population had alcohol (56%) as the etiology followed by gall stones (28%). Outcome assessed at 28 days revealed recovery of 54%, complication of 36% and mortality of 10% of study population. BISAP score computed within 24 hours of admission of 2 or more significantly predicted the severity and complication with P value <0.001. Statistically significant trends of increasing severity and organ failure (P<0.001) with increasing BISAP was observed.Conclusions: BISAP score is a reliable means of predicting the severity and organ failure and stratifying patients with Acute Pancreatitis within 24 hours of admission. The statistically significant incidence of increasing severity and mortality with increasing BISAP score will help us to risk stratify the patients within 24 hours of admission and help improve clinical care and facilitate necessary interventions as early as possible.