Authors examined 40,000 minifilms(boys and girls each 10,000 in junior and senior high schools) which were taken for survey of pulmonary tuberculosis for junior and senior high school students and checked the prevalence of scoliosis. It was considered lateral curvature of spine more than 10 degrees as nonpostural scoliosis, which were analyzed prevalence rate, degree of curvature, distribution of size of curvature, pattern of curve and direction of curvature. Following results were obtained. 1. The overall prevalence rate was 1.56; male 1.38. and female 1.70%(Junior high school 1.06%, Senior high school 2.05%). 2. Scoliosis secondary due to bony abnormality was found in 5 cases. 3. The most common pattern of curvature was the thoracic curve. 4. In sihgle curve, right to left ratio was 1.7, especially senior high school girls had more right curve and junior high school boys had more left curve. 5. The prevalence of senior high school students was greater than that of junior high school students and the degree of curvature was also severe in senior high school students than in junior high school students.