Results indicated statistically significant differences between adult and adolescent parricides. Adults were more likely to suffer from severe mental disorders and have a history of violence and psychiatric problems. Adults were also more likely to have threatened their parents. Adolescent parricides were less predictable in their behavior and as a consequence, several profiles of adolescent parricides emerged that differed in terms of victims’ sex, number of victims, diagnostic elements, and being a witness to or victim of family violence. Adolescents were more likely to assault their fathers or both parents and to have had an accomplice. The findings suggest that adult and adolescent parricides should be approached differently in terms of treatment and prevention strategies. Data were gathered from the treatment records of 43 adult parricides and 12 adolescent parricides hospitalized in a secure hospital for forensic patients or persons presenting with psychiatric dangerousness in Montreal. Data under analysis included information about their mental health, history of family violence, suicide attempts, victimization history, family psychiatric history, and aspects of the offense. Data on the adult and adolescent parricides were compared using the Mann-Whitney nonparametric test. Future research should focus on the psychological factors related to the parent-child relationship in order to better understand the dynamics at play at the time of the offense. Tables, references