Sixty cases of insulinoma were treated surgically. The possible causes for failure to find the tumor during exploratory surgery are discussed. Simple enucleation is preferred in most cases of single or a few insulinomas. A technique of enucleation with minimal chance of injury to adjacent pancreatic ducts and larger blood vessels can be used. When no tumor is found after thorough exploratory procedures, controlled staged resection of the pancreas under blood glucose monitoring is the procedure of choice. Postoperative complications are common but the late results are gratifying provided the operation is carried out early in the course of the disease.