Determination of weekly and daily energy expenditure was made on 62 Republic of Korea Army cadets who were selected at random in order to estimate the weekly and daily ealorie expenditure. Basal metabolic rate (B.M.R.), and energy cost of various military and daily activities were measured by indirect calorimetry using open circuit method. Time-motion studies were also carried on using a stop-watch. The total weekly energy expenditure was calculated by summation of data using energy cost per minute, and the time spent on each activity. Determination of daily energy expenditure was deduced from each data of weekly energy expenditure. Food survey was also carried on for a week, and daily calorie intake was determined by a weekly average discounting loss in cooking. All measurements were determined from the Standard Table of Food Composition published by the Ministry of National Defense (1961). Following data were observed. 1. Physical status of cadets are as follows. Please note that the height and weight averages are 1-2cm and 4-5kg respectively over that of the Seoul National University students. First year Height 167.92 cm (S.D.±4.09) Weight 61.72 kg (S.D.±4.53)> Second year Height 167.89 cm (S.D.±3.46) Weight 63.01 kg (S.D.±4.61) Third year Height 168.15 cm (S.D.±4.24) Weight 43.48 kg (S.D.±5.03) Fourth year Height 168.10 cm (S.D.±3.70) Weight 64.02kg (S.D.±5.10) 2. The B.M.R. of cadets averaged 36.57 Cal./m²/hr) is almost equal with data on the same ages of civilians and the Japanese, but a lower average of 5.1 Cal./m²/hr. than that of a common soldier. 3. The energy expenditure during various military activities is close agreement with Consolazio. Passmore and Durnin, and Japanese reports.