Acute pancreatitis was induced in 139 Wistar rats by injection of trypsin in the common bilio-pancreatic duct. Peritoneal dialysis was performed in 93 rats. In some of these rats, aprotinin (250,000 UI/L) was added to the lavage fluid. Macroscopically, we noted the amount of steatonecrosis, pulmonary congestion and pleural effusion produced. The pancreatic and pulmonary lesions were studied microscopically. The effect of peritoneal dialysis with and without aprotinin on the survival rate was evaluated. Survival curves were established for the different groups of rats i.e. the non-treated group and the two groups of dialysed rats (with and without aprotinin). Peritoneal dialysis reduces the amount of steatonecrosis and the incidence of pulmonary complications of trypsin-induced pancreatitis in rats, but does not influence the pancreatic lesions. Peritoneal dialysis significantly improves the early survival rate. Addition of aprotinin to the dialysis fluid reduces the total mortality rate.