The effect of butylated hydroxyanisole (BHA) and ethoxyquin (EQ) on hepatocarcinogenesis initiated with N-ethyl-N-hydroxyethylnitrosamine in rats was investigated. The results clearly demonstrated that BHA and EQ inhibited the development of gamma-glutamyltranspeptidase - positive foci, hyperplastic nodules and hepatocellular carcinomas in the rat system employed.