The C57BL/6J strain of inbred mice shows a characteristic pattern of ethanol-induced behaviors: very weak acute locomotor stimulation, a lack of locomotor-sensitizing effect of ethanol, and a high level of ethanol intake. This strain has relatively low levels of activity of the ethanol metabolizing enzyme catalase, and it has been proposed that brain catalase plays a role in the modulation of some behavioral effects of ethanol. In the first study of the present paper, we investigated the effects of pharmacological manipulations of brain catalase activity on C57BL/6J mice in acute ethanol-induced locomotion and ethanol intake. Results indicated that the reduction in motor activity produced by ethanol was reversed by pretreatment with catalase potentiators and it was enhanced by catalase inhibitors. In addition, ethanol intake was highly correlated with brain catalase activity in mice treated with a catalase potentiator. In the second study, F1 hybrid mice (SWXB6) from the outbred Swiss-Webster mice and the inbred C57BL/6J mice were used. Basal brain catalase activity levels of F1 mice were intermediate between to those of the two progenitor genotypes. That profile of catalase activity was parallel to the acute-ethanol-induced locomotion and to repeated-ethanol-induced motor sensitization effects observed across the three types of mice. These data suggest that brain catalase activity modifications in the C57BL/6J strain change the pattern of several ethanol-related behaviors in this inbred mouse.