We evaluated the clinical accuracy of an automated turbidimetric assay for serum lipase determination in order to screen for acute pancreatic damage. Seventy patients with pancreatic and thirty with nonpancreatic digestive diseases were studied. Fifty-two healthy subjects were also studied as controls. Serum lipase concentrations were abnormally high in all patients with acute pancreatitis and in 3 (10%) in the group of 30 patients with nonpancreatic acute abdomen. In the 35 patients with chronic pancreatitis studied during clinical remission, serum lipase levels were abnormally high in 8 (23%), and abnormally low in 3 (9%). In the 9 patients with pancreatic cancer, 4 (44%) had abnormally elevated serum lipase values and 1 (11%) abnormally low. The results indicate that serum lipase determination is useful in the emergency diagnosis of acute pancreatic damage because of its high sensitivity and specificity. In patients with chronic pancreatitis and in patients with pancreatic carcinoma serum lipase determination is of limited value.