In equimolar amounts ethanol and trichloroethylene were administered intraperitoneally to male ICR mice in varying sequences. The sequence of administration proved to be decisive for the blood alcohol levels. In relation to ethanol alone following the simultaneous administration of trichloroethylene and ethanol the blood alcohol levels were elevated. This effect is furthermore enhanced if trichloroethylene was administered 1 h prior to ethanol administration. The reversed sequence had no effect on blood alcohol levels.