A continuous production of significant pancreatic enzymes, which are thought to be responsible for the maintenance of the digesting process, is frequently found in fulminant necrotizing pancreatitis. Since the medical therapies known to be effective are based upon the rationale of slowing pancreatic secretion, a simple measure which permits the "burning out" of residual pancreatic tissue might therefore have a therapeutic value. In this study, 2 hr after the induction of acute hemorrhagic pancreatitis, 5 dogs (Group I) were treated with 1.5 ml Ethibloc injected into the pancreatic duct; 5 other animals (Group II) were given 1.5 ml saline; Group III (5 dogs) had no treatment. All animals in Group II and 4 of the 5 animals in Group III expired within 8 days postoperatively. In contrast, 4 of 5 animals from Group I survived. Although some of the biochemical parameters showed significant changes after the induction of acute pancreatitis, no differences were seen between the three groups. In the expired animals, the picture of histological examination was that of a fulminant acute hemorrhagic pancreatitis of the left lobe. In the survival dogs although normal pancreatic tissue was present in the right lobe at necropsy at intervals, there was always a pancreatic atrophy of the left lobe and striking adhesions with the surrounding tissues suggesting the severity of the disease in the acute phase. These findings suggest that pancreatic duct occlusion causing the exocrine secretion to stop may have beneficial effects in the treatment of acute fulminant pancreatitis in the acute phase and may improve the survival rate.