N-Amyl-N-methylnitrosamine (AMN) induced esophageal carcinoma in Donryu strain rats when given in drinking water. The incidence of carcinomas was high when AMN was given as 0.0015% solution for 90 days or 0.003% solution for 60 days. There was no difference in the incidence in males and females. Sequential studies showed that 4-week administration was necessary to induce esophageal papillomas, and 8-week administration to induce esophageal carcinomas. Whole-body autoradiography after intravenous injection of N-amyl-N-methyl[14C]-nitrosamine (14C-AMN) indicated that AMN accumulated preferentially in the esophagus.