Early distinction between acute alcoholic pancreatitis is important, because of possible emergency endoscopic sphincterotomy in case of biliary pancreatitis. The aim of this study was to evaluate the value of L/A ratio in the diagnosis of acute alcoholic pancreatitis. From 1990 to end 1993, 133 patients with acute pancreatitis were reviewed. Inclusion criteria were: 1) abdominal pain, 2) pathological serum amylase or serum lipase on admission or within 24 hours after beginning or abdominal pain, 3) acute pancreatitis at the echography or CT scan within 48 hours after admission. 60 patients met the inclusion criteria (31 alcoholic pancreatitis, 19 biliary pancreatitis and 10 pancreatitis of other causes). L/A ratio was studied in terms of delay from beginning of abdominal pain. There was no statistical difference between alcoholic and biliary pancreatitis at any time of the study, with the exception of admission. AST, ALT and alkaline phosphatase were higher in biliary pancreatitis than in alcoholic pancreatitis. AST and ALT were the best biochemical tests to diagnose biliary pancreatitis. Blamey's criteria can also contribute to diagnose biliary pancreatitis. These biochemical tests are the most helpful if they are collected very soon in the evolution of acute pancreatitis. It is concluded that L/A ratio is not helpful in the diagnosis of alcoholic acute pancreatitis.