The comparison of body composition were studied between 52 nonathletic students and 67 athletic students (weignt lifting, crew, soccer and hockey), aged 18 to 27 years. Boby density determinations were made by water displacement, and the skinfolds were measured at the pressure of 10gm/mm2 with a Minnesota caliper model. The results were as follows: (1) Mean skinfolds were thinner in athletes than in nonathletes at each of various sites measured. The sum values of three sites (arm, back and abdomen) for athletes of each team were 60 to 70% of the value for nonathletes. (2) Mean values of the body density for athletic teams were high, ranging from 1, 073 to 1, 077, as against 1, 069 for nonathletes. The body fats calculated from body density were 8.6 to 10.3% for athletes and 11.7% for nonathletes. (3) When the lean body mass was compared in terms of the relative value of “fat-free weight/height”, the value showed characteristically more marked difference between athletes and nonathletes (31.9 to 36.7 as against 30.8), than in simple comparison of the relative body weight. This index is available for evaluation of active tissue mass individually. (4) The values of “(upper arm girth/π)-(upper arm skinfold)” calculated to evaluate the muscular development were greater in athletic teams (7.30 to 8.20cm as against 6.74cm). (5) The basal metabolism per square meter were 10 to 20% higher in athletic teams, though when it was represented per “fat-free” weight(kg), the difference was reduced to about 7%.