Pancreatic nodules were produced in rats by either feeding raw soya flour alone or by injection of azaserine plus raw soya flour feeding. The resulting nodules were studied to determine whether there was any functional difference between this tissue and the relatively normal internodular pancreas. Tissue DNA and trypsin content were significantly elevated in nodules compared to the adjacent tissue. With fasting, protein and enzyme content increased significantly and equally in both nodular and internodular tissues. RNA levels fell significantly and the decrease was more pronounced in nodular tissue. The responsiveness of the multinodular pancreas to cholecystokinin was examined by measuring pancreatic secretion basally and in response to cholecystokinin. Both the volume and protein content secreted by the multinodular pancreas were greatly elevated above control levels. When corrected for pancreatic weight, the difference remained significant and appeared to be due to increased basal secretion by the nodular pancreas. These studies demonstrate that azaserine-raw soya flour induced nodules are functionally efficient. Furthermore, the secretory response to cholecystokinin of these nodules is equal to or higher than that of normal tissue.