The study was designed to assess the thermoregulatory mechanisms responsible for the elevation in body temperature following ethanol administration when exposed to a high ambient temperature (Ta). Male rats of the Fischer 344 strain were gavaged with 20% ethanol at doses of 0, 2.0, 4.0, 6.0, or 8.0 g/kg and were then placed in an environmental chamber set at a Ta of 37 C. Oxygen consumption (metabolic rate), evaporative water loss (EWL), and activity recorded for 60 min. Colonic temperature was measured at the end of the 60 min period. Ethanol at doses of 2.0 g/kg and greater caused significant reductions in activity. EWL was significantly depressed at doses > 4.0 g/kg. Colonic temperature of animals given 6.0 and 8.0 g/kg was significantly greater than controls. Oxygen consumption was unaffected by ethanol dose. Visual observation of the behavior of the ethanol treated rats indicated that animals given doses > 4.0 g/kg were unable to groom saliva onto their fur which would contribute to the reduction in EWL in the heat.