Background: Acute pancreatitis is a disease with high rate of morbidity and mortality and is known to run an unpredictable course. Computed tomography is the gold standard technique not only for its global picture of the pathology and for the non-invasive method of evaluating the morphology of pancreas and peripancreatic regions in an acute situation. The purpose of the study was to determine the value of computed tomography evaluation in early diagnosis of severity, differences between pancreatitis & acute pancreatitis caused by mass lesions. Methodology: A prospective study comprise of 60 patients on clinical suspicion/diagnosis of acute pancreatitis, altered biochemical parameters (serum amylase, serum lipase) in favor of acute pancreatitis, Ultrasonography suggestive of acute pancreatitis and known case of chronic pancreatitis with features of acute symptoms referred to Department ofRadiology & Imaging, BSMMU, Dhaka, Bangladesh from January to June 2024. Plain and post-contrast series of the abdomen and pelvis were taken. Results: Outof 60 patients, 45 were male and 15 were female patients. Among these edematous pancreatitis was in 20% patients and pancreatic necrosis was in 23.3% patients. Other features like diffuse/focal pancreatic enlargement in (75%), peri-pancreatic fat stranding in (63.3%) and peri-pancreatic fluid collection in (40%). Among this alcohol was the most common cause of AP (83.3%). The accuracy and sensitivity of serum amylase and serum lipase in diagnosing AP were 40% and 63.3% respectively with CT showing 100% accuracy and sensitivity. Modified CT severity index was classified as mild (2 and 4), moderate (6) and severe (8 and 10) of which majority were mild (66%), moderate (22%) and severe (12%). Conclusion: Computed tomography is a sensitive, non-invasive imaging in early diagnosis and staging of severity of acute pancreatitis which help in prediction of prognosis of the disease. It helps to differentiate between edematous and necrotizing pancreatitis as serum lipase and amylase levels do not help to differentiate the type of AP. Modified CT severity index helps in evaluating the percentage pancreatic necrosis and to predict the possibility of developing local and systemic complications and necessity of tertiary care.