In summary, in addition to an acute interstitial pancreatitis the organotin compound DBTC induced a pancreatic fibrosis in rats. The course of the pancreatic fibrosis was studied 2-36 weeks after single i.v. treatment of rats with 6 or 8 mg/kg DBTC. The pancreatic fibrosis induced by DBTC differs from other experimental models of acute pancreatitis. Extensive infiltration by mononuclear cells is present in fibrotic areas without pancreatic atrophy or lipomatosis. The presence of chronic inflammatory lesions characterized by the destruction of exocrine parenchyma and fibrosis and in the later stages the endocrine parenchyma, indicate a chronic pancreatitis. In completion of the experimental model of the DBTC-induced acute interstitial pancreatitis in rats, the described late fibrotic effects on rat pancreas may be used as an experimental model of chronic pancreatitis.