Experi-ments were designed to determine whether changes in the electric potentials of the brain and, concurrently, of the voluntary muscles could be detected after ingestion of alcoholic beverages in amounts producing blood alcohol concentrations lower than 0.05%. Ethanol in amounts corresponding to 0.40 g per kg of body weight was given to 10 subjects as a 12% by volume red dry wine, and to 10 subjects as an 8:1 dry martini cocktail. Analysis of eeg (electroencephalographic) alpha rhythms showed lack of differences between "alcohol" and "alcohol free" experimental conditions in 14% of the data gathered from the wine subjects and in 15% of the data from the martini subjects. Significant increases were observed in 21% of the data from wine subjects and in 11% of the data from martini subjects. Significant decreases were observed only in 2% of the data from wine subjects and in 3% of the data from martini subjects. Analysis of the beta rhythms showed lack of differences between "alcohol" and "alcohol free" experimental conditions in 23% of the data gathered from both vine subjects and martini subjects. Significant increases or decreases were seldom observed. Analysis of the theta rhythms showed lack of differences between "alcohol" and "alcohol free" experimental conditions in 22% of the data from wine subjects and in 35% of the data from martini subjects. Significant increases were observed in 11% of the data from wine subjects and in only 2% of the data from martini subjects. Neither wine nor martini subjects showed significant decreases. Analysis of the delta rhythms showed lack of differences between "alcohol" and "alcohol free" experimental conditions in 17% of the data gathered from wine subjects and in 28% of the data gathered from martini subjects. Significant increases were observed in 14% of the data from wine subjects and only 3% of the data from martini subjects. Neither wine nor martini subjects showed significant decreases. Electro-myograms made during the reaction time experiments showed decreases in muscular tension in a majority of the wine subjects and a slight preponderance of increases in the martini subjects. The data indicate that significant changes in the electric potentials of the brain and of the voluntary muscles occur even at blood alcohol concentrations lower than 0.05%. Moreover, the reactions to equal amounts of ethanol taken as a red wine and as a martini cocktail differ considerably.