This paper deals with a pancreatic function test with the submaximal dose of secretin given by continuous infusion after injection of cholecystokinin-pancreozymin (CCK-PZ) in the submaximal dose. The active elimination of bladder bile by CCK-PZ pretreatment decreased the influence of biliary contamination, and the volume output and the bicarbonate concentration were stabilized by the continuous infusion of secretin. As a result, the coefficients of variation in the volume output and the bicarbonate concentration were calculated to be about 15 and about 5%, respectively. These variations were considerably smaller than those obtained in the standard secretin test. Therefore, the present study is expected to improve the diagnostic means for pancreatic excretory dysfunction.