Background: Sexual violence is considered a serious violation of human rights which affects mainly young women and adolescents. There is little information about the conditions under which sexual offences occur. We evaluated characteristics of sexual violence against adolescent girls and adult women.Method: This is a quantitative, retrospective, descriptive study of sexual violence against adolescent girls and adult women. Analyses were carried out on data collected from 1118 women, 546 adolescents (10-19 years) and 572 adults (>= 20 years), with a complaint of rape treated at Hospital Perola Byington, Sao Paulo, between 1994 and 1999. The age limit of the adolescent sample met the World Health Organization's (WHO) criteria. We analyzed the type of sexual contact, degree of intimidation, perpetrator and activity of the victim during the approach.Results: Crimes without penetration were five times more frequent in adolescents and use of threats of death or intimidation was common in both groups. Mental illness was more prevalent in adult victims and the majority of adolescent victims were aged < 14 years. Uncle and stepfather perpetrators were more frequent among adolescents and partners or former intimate partners in adult women. In most cases the approach occurred in public places, although sex crimes at the perpetrator's residence were more frequent amongst adolescents.Conclusions: Although children and adolescents require the same intervention measures and legal protection, a considerable proportion of adolescent sex offenders can face conditions similar to those of adult women.