Purpose In Sasang Constitution Medicine, persons are divided into four types such as Taeyangin, Taeumin, Soyangin and Soeumin according to their appearance, moral nature and characteristic of constitutional symptoms. In teenager group, diagnosis of constitution based on their appearance was so difficult that we adopted new diagnostic method which measures and compares body compositions. Methods 180 middle school students who live in Pusan were studied from 20th of March, 1999 to 20th of March, 2000. After practicing Questionnaire(I), QSCC(Questionnaire of Sasang Constitution) I , QSCCII, we have measured the height and body compositions with Inbody 3.0, five times. Results 1. The results of Sasang Constitution analysis showed 91 students were classified as Taeumin(50.3%), 75 as Soyangin(41.4%), 14 as Soeumin(7.7%), and 1 as Taeyangin(0.6%). 2. The level of total body water, muscle area, BMR(Basal Metabolic Rate), BCM(Body Cell Mass), and AMC(Arm Muscle Circumference) were increased during spring and summer. That of body weight, fat body weight, fat body weight ratio, waist hip ratio, and BMI(Body Mass Index were increased during fall and winter. 3. In Taeumin and Soyangin groups, the changed capacity of total body water, muscle area and BMR were increased with statistical significance. 4. Waist hip ratio of Soeumin group was reduced more than those of Taeumin, Soyangin groups with statistical significance.