Among several sympathomimetic drugs, isoproterenol, epinephrine and norepinephrine significantly potentiated the cytotoxic effect and the uptake of MMC into rat ascites hepatoma AH130 cells in in vitro experiments, but salbutamol, tulobuterol and phenylephrine did not. The enhancement of MMC uptake into AH130 cells by isoproterenol and norepinephrine was diminished by propranolol but not by phentolamine. These results indicate that the cytotoxic effect and the uptake of MMC is potentiated by the stimulation of beta-adrenoceptors, but not by stimulation of beta 2- and alpha-receptors.