Over recent 20 years, with socioeconomic development and change of recognition of the population, more people are concerned about their health and appearance. To obtain the change of frequency of malocclusion and the demand for orthodontic treatment, with this trend, 2460 freshmen and students of Yonsei Univ. in 1991, aged from 18 to 21 were examined excluding 187 students who have history of orthodontic treatment, 86 students who are undergoing treat?ment, 39 students who have too much missing teeth to classify. After analize the frequency of malocclusion and the demand for orthodontic treatment, following results was obtained. 1. Sex ratio in the prevalence of malocclusion was 91.7%/90.8%, male to female, so there was no sex predilection. 2. With regard to Angle´s Classification, each percentage of Class I, Class II div. 1, Class II div. 2 and Class III was 61.6%.11.3%,1.9% and 16.7%. 3. Of Class I malocclusion, percentage of crowding was 53.2, this occupied the largest part of single findings and prevalent findings in combinations were also crowding - crossbite and crowding - Protrusion. 4. Of Class I malocclusion, over the portion of 95%, Bialveolar Protrusion have arised alone. 5. The distribution of Demands for orthodontic treatment of malocclusion were 41.3% in males, and 51.3% in females.