A simple method for the isolation of intact islets from the normal rat pancreas is described. The method is based upon disruption of the acinar parenchyma by injecting Hanks solution into the pancreatic duct system followed by incubation of the pancreas in collagenase. Islets can be separated rapidly from this mixture by sedimentation. The isolated islets release insulin in vitro and appear normal by light and electron microscopy after incubation. A centrifugation method is also described for isolation of large quantities of islets for biochemical studies.