The present tests were undertaken in order to analyze in male Wistar rats the changes in the exocrine and endocrine pancreas and on the interactions that normally evolve in the insulo-pancreon-axis. To evaluate this by a single i.p. Boots secretin injection, glycemia (G), amylasemia (A) and lipasemia (L) were determined. In bile-pancreatic secretion, we analyzed, pre and post-secretin, the following parameters: volume (V), bicarbonate output (BO), amylase output (AO) and lipase output (LO). Three groups of tests were done: a) control (C); b) streptozotocin-treated non-diabetic-rats (St-ND) and c) streptozotocin-treated diabetic animals (St-D) which showed morning glycemia values higher than 16.0 mmol/l. Four months later, under Tiopental i.p anesthesia, a bile-pancreatic fistula was done. Following a 30 min basal period, Boots secretin (20 CU/kg) was i.p injected. Bile-pancreatic secretion put in evidence a significant fall of BO in both St-ND and St-D series. In controls, AO revealed a post-secretin increase of 160%, while in the St-D rats showed a depression of 41%. The behavior of L was different, being augmented (+27%) in the C, while in the St-D rats the response was significantly higher (+95%). In bile-pancreatic-secretion, the fall of BO and AO in the St-ND and St-D series in respect to the C, are probably consequence of the diminishing potentiating effects exerted normally by insulin on the secretin-induced water and bicarbonate secretion of the pancreon units. In contrast, the rising of LO in the St-D, an expression of an enhancing pancreocyte's synthesis and secretion of lipase. The blood changes of A (depression) and of L (increase) in respect to the C values, although without reaching significant level, mirror those observed in bile-pancreatic secretion.