We evaluated a new continuous colorimetric method for serum lipase determination based on the use of a 1,2-diglyceride as substrate and a specific 2-monoglyceride lipase. This test was compared with a turbidimetric assay and also with serum alpha-amylase and pancreatic isoamylase determinations. We studied 32 patients with acute pancreatitis, 27 with chronic pancreatitis in acute painful relapse, 19 with pancreatic cancer, 44 with other digestive diseases, 53 with end-stage renal disease, and 102 healthy controls. The results of the new test were closely correlated with those of the turbidimetric method (r = 0.96). Sensitivity of the new method was elevated (100%): it was the same as that of the turbidimetric method, but slightly higher than that of alpha-amylase and pancreatic isoamylase determinations (93.7 and 96.9%, respectively). Specificity was 95.5%, i.e. higher than that observed using the other tests (86.4, 84.1 and 88.6% for lipase turbidimetric assay, amylase, and pancreatic isoamylase determinations, respectively). The results demonstrate that this new lipase assay is a sensitive, specific test for the diagnosis of acute pancreatitis.