The present study was initiated to compare the metabolic rate and body heat distribution or two groups or combat infantrymen, Negro and Caucasian, when exposed under identical conditions to standardized cold. The test was designed to simulate conditions as they might exist during forced inactivity in field conditions. Clothing was worn; however, the hands remained bare so as to receive a maximum of cold exposure. The data extend previous observations to include cold air exposure and permit a more detailed evaluation of the over-all thermoregulatory pattern in these two groups of men. The tests were scheduled at the end of the summer and winter in order to determine the influence of chronic cold exposure on these test groups.