In one study, colonic temperature, skin temperature and metabolic rate and, in another study, preferred ambient temperature (Ta) were measured over an 8 hr period in the Sprague-Dawley rat following an intraperitoneal injection of 800 mg/kg sulfolane or physiological saline. At Ta's of 15 and 25 C sulfolane caused a significant inhibition in metabolic rate and reduction in colonic temperature which lasted over the 8 hr measuring period. At both Ta's, metabolic rate tended to recover approximately 4 hr after sulfolane injection. Colonic temperature tended to recover with time but was still significantly reduced at 8 hr post-injection. Tail skin temperature was unaffected by sulfolane. Preferred Ta in the sulfolane-treated rat was not significantly different from the controls. Interestingly, in spite of their hypothermic condition, the sulfolane-treated animals did not select a warm Ta which would have elevated their body temperature to normal.