BackgroundThere is a lack of comparative data on the prevalence and effects of exposure to violence in African youth.AimsWe assessed trauma exposure, post-traumatic stress symptoms and gender differences in adolescents from two African countries.MethodA sample of 2041 boys and girls from 18 schools in Cape Town and Nairobi completed anonymous self-report questionnaires.ResultsMore than 80% reported exposure to severe trauma, either as victims or witnesses. Kenyan adolescents, compared with South African, had significantly higher rates of exposure to witnessing violence (69% v. 58%), physical assault by a family member (27% v. 14%) and sexual assault (18% v. 14%). But rates of current full-symptom post-traumatic stress disorder (PTSD) (22.2% v. 5%) and current partial-symptom PTSD (12% v. 8%) were significantly higher in the South African sample. Boys were as likely as girls to meet PTSD symptom criteria.ConclusionsAlthough the lifetime exposure to trauma was comparable across both settings, Kenyan adolescents had much lower rates of PTSD. This difference may be attributable to cultural and other trauma-related variables. High rates of sexual assault and PTSD, traditionally documented in girls, may also occur in boys and warrant further study.