The diagnostic value of bile salt-dependent lipase for pancreatic diseases was tested in sera of 187 patients. Of these patients, 76 suffered from pancreatic carcinoma, 43 from nonmalignant liver diseases (cirrhosis and chronic hepatitis), 18 from acute pancreatitis, and 20 from chronic pancreatitis. The remaining subjects were controls without pancreatic pathology. Bile salt-dependent lipase was determined by a sandwich enzyme-linked immunosorbent assay using polyclonal antibodies. Amylase and CA 19-9 antigen were also determined. In sera from control patients, the mean level of bile salt-dependent lipase was 1.5 micrograms/L. This level is quite similar to that of patients with benign liver diseases (1.1 micrograms/L) and with chronic pancreatitis (1.4 micrograms/L), but it was raised to 3.5 micrograms/L in patients with acute pancreatitis and decreased to 0.5 microgram/L in subjects with pancreatic adenocarcinoma. Thirty percent of control subjects and 73% of cancer patients had a bile salt-dependent lipase serum level below the cutoff value of 0.5 microgram/L. In acute pancreatitis, 11 of 16 subjects had levels above 1.5 micrograms/L. Amylase level largely increased in acute pancreatitis but was normal in all other groups. Concerning CA 19-9 antigen, 65% of control patients and > 80% of patients with nonmalignant pancreatic or liver diseases had normal levels. In sera from cancer patients, 80% presented with high levels. Accordingly, 36 of 38 patients with pancreatic cancer had either low serum levels of bile salt-dependent lipase (< 0.5 microgram/L) or high values of CA 19-9 antigen (> 37 U/ml; sensitivity 95%).(ABSTRACT TRUNCATED AT 250 WORDS)