An experimental model to perform dynamic studies of exocrine pancreatic secretion from mice has been developed. It consists of a microsurgical procedure in anesthetized mice using a stereoscopic microscope. The bile-pancreatic common duct was individualized, isolated and cannulated. A specially calibrated capillary tube was placed in the free end of the cannula and put on a millimetrical rule. Readings of pure pancreatic juice flow rate were performed minute by minute to obtain a flow rate curve. The procedure allowed the discrimination among increasing betanechol doses of 0.1, 0.2, and 0.4 microgram/g body weight.