To assess the prevalence o sexual violence among adolescents of public schools.Fifty-two public elementary schools of Porto Alegre, Brazil, were selected through random sampling stratified by school size. An 8th grade class was selected in each school through simple random sampling and all adolescents attending the classes who agreed to participate were included in the study. The Screening Survey of Children's Exposure to Community Violence was used to identify adolescents who were victims, witnesses or knew someone who had been a victim of sexual violence.There were 1,193 adolescents included in the study, representing 10.3% of all students enrolled on 8th grade classes in the city's public schools. Twenty-seven adolescents (2.3%) reported being victims of sexual violence, 54 (4.5%) reported witnessing some episode of sexual violence and 332 (27.9%) reported knowing someone who was a victim of sexual violence.Exposure to sexual violence in any of the three forms of contact was a common event among the studied adolescents. Studies focusing sexual violence as a broad social phenomenon with multiples associated factors are necessary to support preventive and treatment strategies at the community level.