<p>Sexual harassment is widespread among adolescents and linked to adverse mental health outcomes. However, little attention has been paid to the gender of the perpetrator and its potential influence on the mental health of the victims. This study examines how the perpetrator’s gender relates to the prevalence and mental health correlates of sexual harassment among Norwegian adolescents aged 13 to 15. Cross-sectional data from 1,988 pupils in 40 secondary schools were used to assess boys’ and girls’ experiences of sexual harassment by both genders and to examine associations with depressive and anxiety symptoms. Overall, boys were more frequently identified as perpetrators, while girls were more often victims. Harassment by boys was associated with higher levels of depressive and anxiety symptoms in both girls and boys. In contrast, harassment by girls was associated with depressive and anxiety symptoms only in girls. The findings highlight the importance of considering perpetrator gender when assessing the impact of peer sexual harassment. Greater attention should be given to the experiences of young adolescents, who appear vulnerable to male-perpetrated harassment in particular. Targeted measures are needed to reduce the mental health burden of sexual harassment, and clinicians should consider these experiences in the assessment and treatment of adolescent anxiety and depression.</p>