Aerobic power of 112 healthy non-athletic and 51 athletic women was measured by the Modified Balke's Method (Treadmill walking) and/or a running method on a motor driven treadmill. Aerobic power for non-athletic women averaged 33.7 ml/kg・min in .20's, 30.3ml/kg・min in 30's, 27.1ml/kg・min in 40's, 24.6ml/kg・min in 50's and 16.8 ml/kg・min in 60's, respectively. These values are similar to that of non-active American women reported by B. L. Drinkwater et al., although the absolute values of aerobic power (1/min) of American women were larger by 14 to 21% than that of our subjects. The following equations were obtained for non-athletic women in the present study. Aerobic power (1/min) = 2.19 - 0.0177 Age (yr). Aerobic power per kg of body weight (ml/kg・min) = 41.83 - 0.337 Age (yr). Maximum heart rate (beats/min) = 205.1 - 0. 776 Age (yr). Oxygen pulse (ml/beat) = 10.76 - 0.054 Age (yr). The mean value of aerobic power was 3.14 1/min (53.1ml/kg・min) for the field handball players of national team (N = 34) and was 2.63 1/min (46.4 ml/kg・min) for the athletes of other events (N = 17). The largest values obtained in the present study were 3.69 1/min (61.0 ml/kg・min) for a boat rower aged 19 yrs, and 61.8 ml/kg・min (3.64 1/min) for a field handball player aged 20 yrs. Aerobic power for non-athletic women was compared with that for girls, which was obtained previously in our laboratory. Aerobic power (1/min) of 20's, 30's, 40's and 50's for non-athletic women corresponded to that of the girls aged 14, 13, 12 and 11 yrs, respectively. The relative values of aerobic power (ml/kg・min) for non-athletic women over 30 yrs of age were smaller than that of any other girls elder than 4 yrs of age.