This study was designed to assess the effects of ethyl alcohol (ethanol) administration on behavioral and autonomic thermoregulation in mice subjected to severe hypothermia or hyperthermia. Male mice of the BALB/c strain were injected intraperitoneally with ethanol at dosages of 0, 0.3, 1.0, or 3.0 g/kg and then placed within a hot environmental chamber to raise their body temperature to 41 degrees C or, alternatively, within a cold chamber to lower it to 28 degrees C. Once the desired hypothermic or hyperthermic state was achieved, the mice were removed from the chamber and placed in either a temperature gradient to monitor behavioral thermoregulatory responses or in an environmental chamber thermostabilized at an ambient temperature (Ta) of 28 degrees C to monitor metabolic rate. The 3.0 g/kg dosage significantly affected behavioral thermoregulatory responses of the hyperthermic mice when initially placed in the temperature gradient. The ability to increase metabolic rate following hypothermia was significantly suppressed at 3.0 g/kg. Dosages of 1.0 and 3.0 g/kg inhibited metabolic rate of hyperthermic mice. Both hypothermic and hyperthermic mice given 3.0 g/kg of ethanol had colonic temperatures significantly below normal after placement in the temperature gradient and metabolic chamber. In conclusion, relatively large dosages of ethanol impair behavioral and autonomic thermoregulation and may lower the set-point for the control of body temperature in mice.