Introduction: Acute pancreatitis (AP) is characterized by a spectrum of symptoms, ranging from a local inammatory process to the more severe form (acute necrotizing pancreatitis) which is associated with a systemic inammatory response. The overall mortality rate of AP is between 5% and 15%, reaching 30 % in severe acute pancreatitis (SAP). Early optimized care may improve prognosis in patients with severe forms but it remains a challenge to identify these poor prognosis cases especially in the rst 48 hours. This study will evaluate the efcacy of serum D-Dimer in prediction of severity and outcome of acute pancreatitis. A prospective observati Methods: onal study of 60 patients presenting with AP was done at st st Silchar Medical College from 1 June 2017 to 31 May 2018. APACHE-II, Ranson criteria, and CT severity index (CTSI) of all patients were calculated,. D-Dimer was done for all patients. The patients were stratied into categories of severe pancreatitis, organ failure and pancreatic necrosis, as well as the number of deaths. The comparison of D-Dimer with other scoring systems was done by area under the receiver-operating curve (AUC) to predict severity, organ failure, necrosis, and death. Of the 60 patie Result: nts, 15 (25%) developed SAP, 12 (20%) Organ failure (OF), 22 (36.7%) pancreatic necrosis and 3 (5%) died. ROC curves were generated and following cut-off were selected for comparison of severity, organ failure, necrosis and death; Ranson ≥ 3, APACHE II ≥ 8, CTSI ≥ 4. Cut-off of D-Dimer value for severity, organ failure, necrosis and death are ≥1397µg/L, ≥1886µg/L, ≥1890µg/L and ≥5769µg/L respectively. The AUC of D-Dimer (0.914) in predicting severity of disease is similar to that of Apache 2 (0.958) and Ranson (0.899). CTSI (0.715) had lowest AUC among them. The AUC of D-Dimer (0.833) in predicting of organ failure of disease is similar to that of Ranson (0.908) and lower than Apache 2 (0.980). CTSI (0.715) had lowest AUC among them. The AUC of CTSI (0.892) in predicting the necrosis was higher than Apache 2 (0.590), Ranson score (0.578) system and D-Dimer. The AUC of D-Dimer (0.953) in predicting of mortality of disease is similar to that of Apache 2 (0.933), CTSI (0.953) and lower than Ranson score (0.816). Conclusion: D-Dimer is an easy tool for assessment of severity and prognosis of acute pancreatitis. CTSI is best for predicting pancreatic necrosis.