Background: Acute Pancreatitis is usually a short-lived inflammatory response to pancreatic gland injury. This study had been proposed to distinguish the etiology of acute pancreatitis by serum lipase/amylase ratio and association between serum creatinine and development of pancreatic necrosis in patients with acute pancreatitis. Materials & Methods: Total five hundred and thirty patients (352 males and 178 females) with acute pancreatitis were selected for the study. The diagnosis of acute pancreatitis was based on clinical evaluation, Computed Tomography findings and biochemical parameters. Based on the etiology, the groups were divided into alcoholic, biliary and miscellaneous. Pancreatic necrosis was assessed by contrast-enhanced computed tomography. Serum creatinine, lipase, amylase and lipase / amylase ratio were calculated and statistically analyzed. Results: At serum lipase/amylase ratio>4.0, sensitivity and specificity for predicting alcoholic group was 61.3 % and 56.0 % respectively. Using 48 h serum creatinine>1.8 mg/dl for pancreatic necrosis, the sensitivity, specificity, positive and negative predictive values were 48.0%, 96.4%, 58.0% and 83.6% respectively. Conclusions: Serum lipase to amylase ratio greater than 4.0 could be used to differentiate between alcoholic and non-alcoholic patients. An increase in serum creatinine within the first 48 h is strongly associated with the development of pancreatic necrosis.