Sexual assault on children and adolescents has become a common topic of study, but there has been little research into the specific characteristics of the population of male victims. A national survey representative of school-age adolescents in France enabled us to study 465 adolescents reporting sexual assault (121 boys, 344 girls; mean age 15.4, SD 2.5 years). Girls were shown to be more frequently affected by certain medicopsychological symptoms: nightmares, multiple somatic complaints and some items concerning mood disorders. On the other hand, behavioural symptoms were much more frequently expressed in boys, in particular: repeated suicide attempts, running away, fits of violence and substance use. Boys presenting these symptoms should be questioned as a matter of routine concerning a history of sexual assault.