The relation between plasma and biliary amylase activity and their relationship to the functional state of the pancreas were studied in anesthetized rabbits. Repetitive intravenous injections of cholecystokinin resulted in a 25-fold rise in the secretion of amylase via the pancreatic duct, followed at first by a 50% increase in plasma amylase concentration and later by a 270% increase in biliary amylase concentration. There was then a gradual, roughly synchronous decline in both plasma and biliary values toward basal level despite a continued highly augmented rate of pancreatic ductal secretion. "Near-total" pancreatectomy completely abolished the effect. These observations are consistent with a cholecystokinin-induced basolateral secretion of amylase from pancreas into blood and its subsequent movement from blood into bile down a concentration gradient. The output of amylase in bile, however, was quite small and does not suggest that biliary transport of amylase has an important function either as a means of secreting and recycling digestive enzyme into the gut or as a major excretory pathway for circulating amylase in the rabbit.