Introduction: Acute pancreatitis (AP) is a very common health problem which requires proper evaluation and timely management in higher centers. Acute pancreatitis is characterized as a pancreatic inflammatory condition that may result in multi-organ dysfunction and a higher death rate. The methods that are currently available to evaluate the severity of acute pancreatitis are costly and are not easily available in primary health level. The BISAP (Bedside Index of Severity in Acute Pancreatitis) is new scoring system which can be used to measure the severity of the acute pancreatitis at the time of admission with routine blood test and clinical evaluation. Severe acute pancreatitis has high mortality rate and it needs intensive management. Hence early prediction of severity and diagnosis is very important Therefore a study was conducted to evaluate the effectiveness of BISAP scoring system, which is done on day one of admission, in predicting the severity of acute pancreatitis in settings, so as to divide the patients into low risk and high risk based on score, and can give more and intense care to high-risk group. Objectives: To evaluate the diagnostic efficacy of BISAP scoring system on predicting severity of acute pancreatitis in the Department of Gastroenterology, PRS Hospital Thiruvananthapuram. Methods: A cross sectional study was conducted over cases of Acute pancreatitis those are admitted in the wards of Medicine, Surgery and Gastroenterology department of PRS Hospital, Thiruvananthapuram, satisfying the inclusion criteria for a period of 1 year. Their clinical features, laboratory results and imaging modalities were recorded. All patients admitted were scored with BISAP scoring system at the time of admission, and they were followed up after 7 days and 6 weeks and the result is compared with acute pancreatitis severity grading based on Revised Atlanta classification 2012. Data entered in to an excel sheet and analysis done using appropriate statistical software. Results & Discussion: In the study, out of 120 patients studied 98 were males and 22 were females with mean age of 44.4±14.8. Of these, 94 had mild acute pancreatitis, 8 had moderately severe and 18 had severe acute pancreatitis (Revised Atlanta classification 2012). 26 of the studied cases have BISAP score as severe acute pancreatitis. In the present study, the sensitivity obtained was 100, specificity was 92.2 and accuracy was 93.3, Positive Predictive value (PPV) of 69.2, Negative predictive value (NPV) of 100. There were 12 early deaths in the study, of that; all of them were remarked by BISAP score as severe acute pancreatitis. The BISAP score had a sensitivity of 100% in predicting early deaths. It had a NPV of 100% which means the patients are unlikely to die due to AP, if they do not have severe acute pancreatitis by BISAP score (p value of <.01). The diagnostic accuracy of BISAP score for males and females are 91.8 and 100% respectively. The diagnostic accuracy of BISAP score for age<40 and age>40 are 96.8 and 89.7 respectively. Conclusion: BISAP scoring system is a good predictor of severity in acute pancreatitis. It can also be used to predict deaths in acute pancreatitis. BISAP score can be used as an effective tool in order to stratify patients according to their severity, thereby helping to reduce the mortality and morbidity. as we can divide the patients into low risk and high risk based on score, and can give more and intense care to high-risk group.