The effect of chronic ethanol intake on neuromuscular function has been analyzed by using a rat tibial muscle preparation. The time-course of single twitches, trains-of-four, tetanus and post-tetanic facilitation with and without blockade with alcuronium was evaluated. A decrease in these parameters was observed, being more pronounced in ethanol fed rats during 10 than 30 days. The twitch was the most affected parameter. After recovery of alcuronium blockade, the depressant effects of ethanol were completely reversed. These data suggest that low but sustained ethanol blood levels causes evident alterations of neuromuscular function due, probably, to a postjunctional action.