Purpose: This study was conducted as a descriptive one for the purpose of determining the factors affecting the beliefs and social distances of adolescent high school students for mental illnesses. Materials and Methods: Research that conducted in the spring semester of the 2014-2015 academic year at four high schools of the District Directorate of National Education in a district in the West, the target population of the study consisted of 727 high school students and research sample consisted of 480 students. In the research, a questionnaire form which were prepared in accordance with the literature information, Beliefs Scale Toward Mental Illness and a Social Distance Scale were used. Results: 97.7% of students had no mental illnesses in their families, 49% of them defined mental illness as mental disorder. The point average of Beliefs Scale Toward Mental Illness was 54.17 ± 16.56; the point average of Social Distance Scale was found to be 68.11 ± 20.89. Beliefs toward mental illness were found more negative in males, in those who did not have received treatment for mental illness before, those who think that individuals with mental illness should not be intertwined with the public and those who associate mental illness as losing mental balance and definition of madness. Conclusion: Students who did not receive treatment for mental illnesses and who thought that individuals with mental illness should not be intertwined with the society, were found to have a higher tendency to both negative belief in mental illnesses and social distance to mental illnesses.Factors affecting the beliefs toward mental illnesses and social distances of high school students Hülya Arslantaş1 , 2 , Ezgi Sarı1