Segmental pancreatic allotransplants were performed intraperitoneally in pigs with and without ligation of the duct. Exocrine pancreatic function was suppressed by the administration of glucagon. All recipients also received high doses of methylprednisolone for the first 10 days after transplant as well as cyclophosphamide until death or sacrifice. Some animals received antilymphocyte globulin (ALG) in addition. Diabetes was induced by total panreatectomy. Allotransplantation in pancreatectomized animals was successful in preventing hyperglycemia for up to 33 days of observation. ALG in the dosage used did not show any beneficial effects and varying degrees of rejection occurred in the majority of these unmatched animal pairs. Grafts without ligation of the duct seemed to show the best preservation of tissue because of absence of obstructive damage following duct ligation. Of significance is the fact that no intraperitoneal inflammatory or infectious complications occurred in recipients of either duct-ligated or unligated grafts, presumably because of suppression of exocrine function with glucagon and the reabsorptive capability of the peritoneal surface. We speculate that this is a satisfactory physiological model for continued trials in pancreatic transplantation, although antirejection therapy was far from satisfactory.