Thermoregulation of the mesic-habitat Cape mole rat, Georychus capensis (mean mass 193 g), was investigated, and the data was used to test the hypothesis that exceptionally low mass-specific rates of metabolism are common to the arid-habitat subterranean rodents only. The mean body temperature was 36.4 C, resting metabolic rate was 68% of that expected for rodents, and conductance was 62% of the predicted value. This mole rat maintained a constant body temperature independent of ambient temperatures between -0.5 and 28 C. The data refuted the above hypothesis. A possible explanation for the low rate of metabolism of G. capensis is given.