As depression is a state of pathological sadness which causes disability especially in adolescents, our objective is to determine the factors involved in depression among high school students in Antananarivo in aim to improve their care. This descriptive study was conducted in four high schools in Antananarivo, for the second and first grade classes of the school year 2017- 2018. Depression was evaluated by the Major Depression Inventory for Children. Data was analyzed by using the software Epi info 7, with a significance threshold p at 0.05. Thus three hundred and three (N = 303) youngsters were included in the study, with 124 boys and 179 girls (sex ratio = 0.69). More than half of the depressed population (59.57%) was an adolescent girl. Among the depressed teens, 53.62 % were from a middle-income family. Sixty-four percent of non-depressed adolescents were enrolled in public high schools. Moreover, teenagers with a good relationship with their parents were not depressed. Furthermore, depression was mostly found in adolescents with a medium-quality relationship with their teachers. Last, depressed students had average school performance in 79.86% of cases. All in all, depression in high school students deserves our attention in our therapeutic interventions. These young people are not priority because they don’t disturb well-being of the class. Thus, qualified staff in each educational establishment would be beneficial and should be adopted.