This article presents the main results of the National Adolescent School-based Health Survey (PeNSE). A questionnaire was applied to a sample of 60,973 students of the 9th year of Junior high school in public and private schools of the Brazilian state capitals and the Federal District, between March and June 2009. The prevalence and confidence interval of 95% (CI 95%) of the violence situations involving adolescents were analyzed. The following situations were identified: lack of safety on the way home-school (6.4%; CI95%: 6.1%-6.8%) and at school (5.5%; CI95%: 5.2%-5.8%); involving fights with physical aggression (12.9%; CI95%: 12.4%-13.4%), with knife (6.1%; CI95%: 5.7%-6.4%) or fire arm (4.0%; CI95%: 3.7%-4.3%); physical aggression by family member (9.5%; CI95%: 9.1%-9.9%). Violence situations were more prevalent among male students. There were great variations among the cities studied. Adolescents are exposed to different violence manifestations in the institutions that supposedly must assure their protection and healthy development: school and the home. These results aim to support health promotion measures and prevention of these risk factors.