The maximal oxygen intake (MOI) was determined in 54 males (23 nonathletes, 10 basketball players, 8 hand ball players, 7 weight lifters and 6 long distance runners) and in 49 females (24 non-athletes, 16 basketball players and 9 volley ball players) by using a treadmill method outlined in Part I of the present investigation and the following results were obtained: (1) The maximal aerobic work capacity varied from the lowest value of 1,008 kg-m/min in female non-athletes to the highest value of approximately 2,000 kg-m/min in male basketball players and long distance runners. Values of other groups varied from 1,400 kg-m/min in male non-athletes and female athletes to 1,800 kg-m/min in male hand ball players. (2) The MOI per unit body weight varied from the lowest value of 41.3 ml/min/kg in female non-athletes to the highest value of 67.6 ml/min/kg in male long distance runners. Values of other groups were in the order of 47 to 55 ml/min/kg. (3) The heart rate during maximal aerobic work performance varied from the lowest value of approximately 180 per min in female basketball players and male long distance runners to the highest value of 190 or above in nonathletes of both sexes. (4) An estimate of oxygen debt as measured during 15 minutes following the maximal work was 3.841 in female non-athletes, 4.681 in female athletes, 5.561 in male non-athletes and 6.321 in male athletes. These results indicate that the MOI per unit body weight as well as the oxygen debt of Korean non-athletes were comparable to, while corresponding values of Korean athletes were considerably lower than, those of other countries such as Japan, the United States of America and Europe.