The pancreolauryl test is marketed as a tubeless test of pancreatic function based on the specific splitting by pancreatic esterase of orally administered fluorescein dilaurate. The test was evaluated in 50 patients, all of whom had at least 1 other pancreatic function test (secretin-pancreozymin, Lundh, BP PABA[blue tetrazolium-p-aminobenzoic acid]/14C index). The sensitivity of the pancreolauryl test was 75% if equivocal results (T/K 20-30) were excluded and 77% if the equivocal results were included among the abnormal results.sbd.figures which were similar to those obtained for the other 3 function tests. However, the specificity of the pancreolauryl test was 60% if equivocal results were excluded, decreasing to only 39% if equivocal results were considered to be abnormal. The false-positive tests chiefly occurred in patients who had previously undergone gastric or biliary bypass or vagotomy and echolecystectomy (BT PABA/14C test normal). These data, and the known dependence of esterase activity on bile salts, suggest that the pancreolauryl test assesses the combined functional efficacy of secreted esterase and bile salts. Despite the test''s high sensitivity, its low specificity makes it unreliable as a test of pancreatic function per se. The pancreolauryl test may be particularly useful in evaluating patients with bile-pancreatic juice admixture problems.