The secretin stimulation test is the most sensitive and specific test for pancreatic function. It is usually performed using biologically derived porcine secretin. Several shortages of biologic porcine secretin have occurred in the past few years. The aim of this study was to compare synthetic porcine secretin to biologic porcine secretin in pancreatic function testing in subjects with chronic pancreatitis. Twelve patients with a previously abnormal secretin stimulation test were enrolled. After an overnight fast, each patient underwent a secretin stimulation test on 2 consecutive days using 1 CU/kg biologic porcine secretin or 0.2 [microg/kg synthetic porcine secretin in a randomized fashion. The peak bicarbonate concentration in duodenal juice was used as a measure of pancreatic function. The peak bicarbonate concentration (mean +/- SD) obtained by using biologic porcine secretin and synthetic porcine secretin were 70 +/- 25 mEq/L and 68 +/- 31 mEq/L, respectively (p = 0.58, paired t test; R = 0.964). The accuracy of synthetic porcine secretin in diagnosing pancreatic insufficiency was 100% when compared with biologic porcine secretin. We conclude that synthetic porcine secretin is highly accurate and safe in pancreatic function testing. The 100% purity, excellent diagnostic accuracy, and ready availability make synthetic porcine secretin an attractive choice for secretin stimulation testing.