Ten healthy male subjects ingested ethanol (BP; 0.5 g/kg body weight) after an overnight fast, on two separate occasions, at environmental temperatures of either 21 degrees C or 30 degrees C. The mean maximal fall in deep body temperature was not significantly different on the two occasions, being 0.18 degrees C and 0.17 degrees C respectively. Metabolic rates throughout the experiments at the two temperatures were not significantly different. The vasodilatation of the hand and forearm vascular beds after ethanol ingestion was markedly reduced at the lower environmental temperature. In three subjects who ingested a higher dose of ethanol (BP; 1.0 g/kg body weight) after an overnight fast, at an environmental temperature of 21 degrees C, the mean maximum fall in core temperature was 0.15 degrees C, which was not significantly different from the change seen after consumption of the lower dose of ethanol. It is likely that the failure of ethanol ingestion to provoke hypothermia at the lower environmental temperature was due to the attenuated vasodilatation observed under these conditions.