SummaryPancreatic juice was collected from rabbits treated with reserpine and from untreated controls. The volume of pancreatic juice secreted, flow rate and the bicarbonate output were all significantly reduced in the treated animals during both spontaneous flow and during secretin-stimulated flow. On the other hand, the total protein concentration, the amylase activity and the calcium concentration of the pancreatic juice were all significantly elevated in the treated animals. The elevation in the total protein concentration appeared to be due to both increased amounts of protein and decreased amounts of water. Of particular interest was that secretin stimulation caused the same % increase in the flow rate and output of pancreatic juice in both control and reserpine treated rabbits. The method by which fluid is secreted by the treated animal, therefore, appeared to be depressed at all tunes and under all conditions. Decreased volumes of pancreatic juice, a decreased bicarbonate output and increased concentrations of protein and calcium are found in this model and are consistent with clinical findings present in the pancreatic secretions obtained from individuals with cystic fibrosis. Therefore, the similarities between secretions of the reserpine treated rabbit and those observed in the cystic fibrosis patient support its use as an experimental model for investigating the abnormal pancreatic secretions in this disease.