Chronic drainage of pancreatic juice in rats results in a non-parallel secretion of digestive enzymes. The concentration of trypsinogen, chymotrypsinogen, procarboxypeptidase B and lipase increases continuously whereas that of amylase drops. An amino acid mixture given intravenously does not affect this dissociation. Reinfusion of bilio-pancreatic juice into the duodenum on the contrary influences the relative enzyme release: the increase in concentration of the three proteolytic enzymes and of lipase is less pronounced over the 72-hour study period; amylase concentration remains unaffected. In the absence of an intravenous amino acid feeding the pancreatic protein output is more than halved and a negative nitrogen balance is observed. Reinfusion of bilio-pancreatic juice does not alter the total protein output. This report confirms the persistence of a dissociation in the rate of enzyme release in rats with chronic pancreatic fistula despite sufficient protein administration and intestinal reintroduction of bilio-pancreatic juice.