Caraway oil, supplemented in diet or painted on the skin, inhibited 7,12-dimethylbenz[a]anthracene- (DMBA) and croton oil-induced skin tumors in female BALB/c mice. The inhibition was manifested by disappearance of carcinomas, reduced incidence and number of papillomas, delay of their appearance, retardation of their development, and regression of already established papillomas. Caraway oil is more effective when topically applied than when supplemented in the diet.