The influence of ethanol consumption on acetylcholinesterase (AchE) and Na+, K+ -ATP-ase activities was examined in 14 healthy volunteers after 30 minutes of ethanol treatment at a dose 0.6 g/kg of body weight. It was observed that the activity of both enzymes decreased. The activity of AchE was significantly lower, and that of Na+, K+ -ATP-ase tended to be lower, but the difference was not significant. In vitro experiments showed that ethanol inhibited the AchE and N+, K+ -ATP-ase activities immediately and in proportion to the concentration of ethanol used.