Arterial concentrations and arterio-jugular vein differences of ethanol, acetate, glucose, lactate, pyruvate, glycerol, free fatty acids and ketone bodies were determined in seven healthy male volunteers before and during an infusion of ethanol, which gave a blood alcohol concentration of about 12 mmol/l. Arterial-jugular vein (A-JV) oxygen differences were unchanged throughout the study. Ethanol caused a small reduction in blood glucose concentration, from a mean of 5.1 to 4.7 mmol/l, and the A-JV difference fell significantly. When alcohol was given, arterial acetate concentration rose quickly to about 1 mmol/l and was unchanged thereafter. All subjects had a positive arterio-venous difference for acetate. Arterial lactate concentration was doubled by ethanol and the normal release from the brain was abolished. Arterial alanine concentration decreased significantly, from 0.19 to 0.16 mmol, when alcohol was given but no net exchange by the brain could be observed. It is concluded that: (a) acetate can be taken up by the brain and if totally oxidized, could account for 6% of the oxygen consumption; (b) glucose arterial-jugular vein difference is decreased by ethanol, suggesting an attenuation in glucose uptake; and (c) lactate net release is abolished by alcohol, probably due to the increased arterial concentration.