BACKGROUND: Open multidisciplinary centers were operated in the mid 1990s for victims of sexual assaults in Oslo and Reykjavik. However, in Copenhagen and Helsinki forensic medical examination was only available to victims who reported directly to the police. One of the main aims of this study was to compare the effect of these different service facilities in four Nordic capitals on the victims' frequency to seek help and report sexual assaults to the police. METHODS: The age and attendance profile of 380 individuals, seeking support after sexual assault, was compared for the four capitals over a period of 1 year. The circumstances and consequences of assault, frequency and time lag of reporting were also compared. RESULTS: Open centers received several times more victims, especially in younger age groups, including more reported cases, when compared with the population at risk than forensic institutes. Victims were seen earlier for examination at forensic institutes that dealt with a more limited spectrum of sexual assaults than the open centers. The proportion of rape was higher amongst victims brought to forensic institutes whereas a higher proportion of victims received at open centers had been exposed to less violent assaults. The frequency of visits was higher at weekends, between 50% and 70% of victims reported consumption of alcohol, and one-third were attacked while sleeping. In the majority of cases only one perpetrator was involved, most often unknown or peripherally known to the victim. CONCLUSION: Open multidisciplinary centers receive and assist considerably more victims, reporting and not reporting sexual assaults than forensic institutes.