An analysis of data from the Swiss Multicenter Adolescent Survey on Health was conducted to assess the prevalence of a history of sexual victimization among a national sample of adolescent girls enrolled in schools or professional training, to estimate the number of associated psychosocial health problems, and to gain information on the effects of disclosure of the experience. A representative sample of 9268 adolescents answered a written questionnaire on health and lifestyle. Of the 3993 participating girls, 18.6% reported an experience of sexual victimization. The burden of associated psychosocial health problems was considerable, notably as regards depression, suicidal behaviour and substance misuse. Preliminary findings on the relation of disclosure and mechanisms of learned helplessness stress the need for more research on this issue. The results stress the importance of prevention programmes for adolescents and preadolescents, of physicians' awareness and training for screening and appropriate counselling, and of easy access to professional support.