The aim of the present study was to compare the psychosocial profiles of criminal homicide victims with those of a matched sample of perpetrators. The hypothesis was that chance determines whether someone becomes a victim or a perpetrator. In a retrospective examination of forensic psychiatric records as well as hospital records, the following variables were studied: nationality, education, substance abuse and psychiatric diagnoses. A comparative study was performed of 88 perpetrators and 83 victims in Sweden during a time period of 17 years (1978-1994). All subjects had been treated as psychiatric inpatients before the homicide. The results support the hypothesis that perpetrators and victims of homicide are similar with regard to psychiatric morbidity and social functioning. The majority were born in Sweden, and the educational level was low in both groups. Substance abuse was common in both groups: 96.7% of male and 65.3% of female victims compared with 76.6% of male and 75% of female perpetrators. Many in both of the groups had criminal records. The only major difference between the groups was recorded for psychotic disorder diagnoses, with a higher rate among perpetrators as well as a lower rate of substance abuse in this group.