A detailed survey of nutrition and energy expenditure was undertaken to establish the effects of chronic cold exposure and changing levels of activity upon the nutritional requirements of men living at an Antarctic base. This survey represented 104 subject days (6-day periods) in the Antarctic fall, winter, and spring. In the fall, five scientists averaged a daily expenditure of 3775 Calories and consumed 3400 Calories (42 Cal/kg/diem). In the winter and spring, expenditures for four scientists averaged 3370 and 4175 Calories and intakes were 4396 and 4285 Calories (53 and 54 Cal/kg/diem). Four sailors, engaged in moderate to heavy work outside, expended about 3600 Calories per day and consumed. 4925 Calories (61 Cal/kg/diem) when studied in the spring. The percentage of calories furnished by protein, fat, and carbohydrate was not significantly different from those to be found in the diet of U.S. troops eating a garrison ration elsewhere. There was no increased avidity for fat over the year. The scientists gained an average of 1. 5 kilograms in body weight, and the sailors an average of 4. 6 kilograms over the 11-month period. It is suggested that eating served to alleviate the tedium of long isolation and that psychological, as well as physiological, reasons lay behind the high caloric intakes seen in some subjects.