The possibility that rioprostil can prevent cyclosporin A-induced damage to the pancreas is investigated. Cyclosporin A is given to rats once daily intragastrically in doses of 5, 10 and 20 mg/kg body weight. These doses cause dose dependent significant reduction of insulin release and enzyme secretion from the arterially perfused isolated pancreas. The subcutaneous injection of rioprostil, 15 micrograms/kg twice daily, could completely prevent the effects of 5 mg/kg cyclosporin A on insulin release and could completely prevent the effects of 5 mg/kg cyclosporin A on insulin release and could completely prevent the effects of 5 mg/kg cyclosporin A on insulin release and could also afford significant protection from the effects of 10 and 20 mg/kg cyclosporin A on both insulin release and enzyme secretion. The cytoprotective action of rioprostil on the pancreas may have therapeutic implications.