T-2 toxin is one of the important representatives of trichothecin metabolites of Fusarium species. Various proliferative changes in epithelia of forestomach including papillomas were induced in mice after prolonged feeding of T-2 toxin by intubation at 0.1 mg/kg, 3 times a week for 25 weeks. The incidences of hyperkeratosis, papillary hyperplasia, moderate dysplasia and papilloma were 82.9%, 28.6%, 42.9% and 14.3% respectively. The earliest papilloma in forestomach of mice occurred as early as 6th week of the experiment. While in forestomach of mice in the control group, only 4.20% hyperkeratosis and 4.2% simple hyperplasia were found, no papillary hyperplasia or papilloma occurred. The above results indicate that T-2 toxin has a selective tumorigenic effect on the forestomach which is actually the extension of the esophagus in mice. These findings may give important hint to the study of human esophageal carcinogenesis.