The present study was conducted with the aim of investigating the mental health of high school students in Ilam province based on gender differences. This research is practical in terms of purpose and quantitative in terms of implementation, and it was carried out in a descriptive manner. The statistical population of the research includes all the male and female students of the first year of high school in Ilam province in the academic year 2018-2019, from which a sample of 378 people was selected by multi-stage random sampling. The required data were collected through Goldberg's 28-question general health questionnaire and diagnostic interview. The findings of the research showed that according to the scores of the questionnaire, 20.7% and according to the results of the interview, 17.74% of the statistical sample have problems in the field of mental health. The rate of mental health problems was 16.3% among boys and 25.3% among girls. In the four dimensions of health, 29.8% had problems with social dysfunction, 19.1% with anxiety and insomnia, 16.1% with depression, and 14% with physical symptoms. Multivariate analysis of variance showed that girls have more problems in health, anxiety, depression and physical symptoms than boys and this difference is statistically significant (P<0.05). The findings also showed that there is no difference between the health of students according to their parents' age, educational level and occupation. The results of the research indicate the necessity of implementing programs to improve the mental health of students during adolescence by health officials and parents of education