In an examination of the effect of ischemia and reperfusion on the generation of active oxygen species during pancreatic cell damage, a short-term ischemia and reperfusion model was prepared by the occlusion and reperfusion of both the anterior mesenteric artery and the celiac artery in rats. Following 60 minutes of occlusion plus 7 hours of reperfusion of the anterior mesenteric artery and the celiac artery, the serum concentrations of amylase and lipase rose significantly to 7 and 6 times the respective control values. After 30 minutes of occlusion plus 7 hours of reperfusion, or after 7 hours of occlusion without reperfusion, amylase and lipase levels were not changed significantly. The continuous intravenous infusion of superoxide dismutase (3600 U/kg/hour) in rats receiving 60 minutes of occlusion plus 7 hours of reperfusion suppressed the rise in serum amylase and lipase values to 25 percent of the values in the non-injected group. These results suggest that the active oxygen species which are generated by the short-term ischemia and reperfusion method injure the endothelium and cause hyperamylasemia and hyperlipasemia. Inhibition of the rise in serum amylase and lipase concentrations by pretreatment with a scavenger of active oxygen, superoxide dismutase, suggests that the active oxygen species are involved in the pathogenesis of acute pancreatitis.