Objective To establish an effective exercise prescription, the exercise capacity of obese subjects was investigated Methods In 71 male obese (body mass index: BMI≥26 4) Japanese, aged 26-77 years, the body composition and physical fitness such as aerobic exercise level, muscle strength and flexibility were determined and compared with those of age and sex matched 71 borderline (24 2≤BMI<26 4) and 71 normal Japanese men (19 8≤BMI<24 2) The relationship between body composition and other parameters was evaluated in obese subjects Results In obese subjects, body weight, BMI, body fat percentage, waist hip ratio, and skinfold thickness were higher than those of borderline and normal subjects Lower aerobic exercise level and weight bearing index (WBI) were noted in obese subjects There was a negative correlation between waist hip ratio and aerobic exercise level (oxygen uptake at ventilatory threshold) ( r =-0 509, P <0 01) and also between waist hip ratio and WBI ( r =-0 315, P <0 01) Conclusions Lower physical fitness is considered to be a general characteristic of male obese Japanese, and the accumulation of visceral adipose tissue might affect exercise capacity Objective To establish an effective exercise prescription, the exercise capacity of obese subjects was investigated Methods In 71 male obese (body mass index: BMI ≥ 26 4) Japanese, aged 26-77 years, the body composition and physical fitness such as aerobic exercise level , muscle strength and flexibility were determined and compared with those of age and sex matched 71 borderline (24 2 ≦ BMI <26 4) and 71 normal Japanese men (19 8 ≦ BMI <24 2) The relationship between body composition and other parameters was as obese subjects Results In obese subjects, body weight, BMI, body fat percentage, waist hip ratio, and skinfold thickness were higher than those of borderline and normal subjects Lower aerobic exercise level and weight bearing index (WBI) were noted in obese subjects There was a negative correlation between waist hip ratio and aerobic exercise level (oxygen uptake at ventilatory threshold) (r = -0509, P <0.01) and also between waist hip ratio an Conclusions Lower physical fitness is considered to be a general characteristic of male obese Japanese, and the accumulation of visceral adipose tissue might affect exercise capacity (r = -0 315, P <0 01)