This study was conducted to find out the mental health state of high school students. First-year students and third-year students af liberal high schools is Seoul were subject to this study. Questionnaire of Symptom Checklist-90 and various factors was adopted for the survey. A total of 916 questionnaires was sellected for the analysis, and the results are obtained as follows; 1) The characteristics in responses to mental health scale showed that obsessive-compulsive scale score was the highest, followed by interpersonal-sensitivity, depression, hostility, and anxiety. The subject group of the students showed higher scores in nine symptom dimensions except somatization than other normal group. 2) Girl-students showed higher scores than boy-students in somatization, depression, and anxiety, whereas the opposite was true in hostility. 3) Third-year students got high scores, in somatization, anxiety and Depression. 4) Parental marriage state of the repondents showed significant differences in nine symptom dimensions of mental health. Scores of the students with parents was the lowest, followed by those of students with only mother, only father and the rest(no parents, divorced, sepaerated, step-parent) in increasing order. 5) Smoking students showed high score in obsessive-compulsive, depression, hostility, paranoid ideation, and psychoticism. Especially in hostility, they got much higher score. 6) Students with poor record at school got higher scores in every symptom dimension than those with good record at school, especially in obsessive-compulsive and depression scale. 7) Parents' attitude toward student showed significant effect on every scale. Students under over-expectation or indifference from parents were in bad mental health state. 8) Students who have advisor proved to be in better mental health state than those who never consult their personal problems with others. 9) He who has family history got higher scores in some scales. 10) Respondents who looked upon what they have learned in high school as being rather an obstacle to sound social life got high scores in all the symptom dimensions and next came those of the students who answered that there were a lot of unnecessary things in their learning. 11) Those for whom it would not quite necessary to enter college if there were little formal schooling discrimination in society got high scores in obsessive-compulsive, interpersonal sensitivity, depression, hostility, and in psychoticism, especially higher in obsessive-compulsive scale. 12) Mental health state of the students who are influenced by the social surroundings, mass media, and the home environments showed high score in 8 symptom dimensions. 13) Abnormal response frequency of this sample is as follows; 24.0％ of boys, 23.8％ of girls, 22.5％ of the first-year students, and 26.9％ of the third-year students. There were significant difference among the grades. 14) The factors of distinctive correlation between the dimensions of SCL-90 and 16 factors were the father's negative attitude and depression, negative responses on teaching contents and anxiety, and smoking and hostility. In conclusion, mental health state of liberal highschool students on the whole showed worse than other normal groups. It had close terms with relation with their parents, schoolwork, smoking, teaching contents, the social surrounding, mass media, and the home environments. Thus I believe there need not only mental health education of students, training of teachers, counceling of parents, but also changes in teaching contents, and the improvement of educational system and the social surroundings under the national support.