Although pancreozymin-secret in tes t is a rel iable examinat ion of pancreat ic exocrine function, pancreat ic juice, bile and intest inal juice, secreted f rom the intest inal wall, are mixed in duodenal juice taken by th is measure , and it is impossible at present to obtain pure pancreat ic juice. The authors util ized this disadvantageous phenomenon of bi le contaminat ion in this method for differential diagnosis of the diseases in the b i l ia ry t r ac t and pancreas, by multifying ic terus index of duodenal juice by its volume and observing fluctuation of bile excretion. Bile excret ion was the m ax i m um for 10 minutes a f te r injection of panereozymin in normal men, and bicarbonate sal t was most r emarkab ly excreted for 10 to 20 minutes af ter injection of secretin. In most cases of chronic pancreat i t is , decrease in bile excret ion could be observed, while in cases of carc inoma in the bi l iary t r ac t or in the head of the pancreas bile excret ion was scarcely observed. Decrease in secretory function of b icarbonate sal t was s l ight in cases of carcinoma in the bi l iary t ract , whereas in cases of carc inoma in the head of the pancreas excret ion of b icarbonate sal t could not be observed at all. F luc tua t ion of bile excret ion in cases deprived of function of the gall-bladder was character is t ic , and bile excret ion sl ightly increased af te r injection of pancreozymin, which was maintained in tha t level for long thereaf ter . In order to clar i fy qual i ta t ive and quant i ta t ive relat ionship in pancreat ic juice, bile and intest inal juice af te r injection of pancreozymin and secretin, a vinyl tube was inserted into the pancreat ic duct and common bile duct in mongrel dog and pancreat ic juice and bile was respectively collected. The same procedure was per formed in two cases of choleli thiasis . F rom these exper iment , it was assumed tha t secret ion of pancreat ic juice is s t imula ted by injection of pancreozymin to some extent , and intest inal juice is secreted more than 20 cc for 10 minutes a f te r injection of secretin, considerable amount of bicarbonate sal t being contained in bile, and it was fu r the r concluded that const i tut ion of pancreat ic juice, bile and intestinal juice in duodenal juice obtained in this examinat ion is a complicated one.