Psychological determinants of aggressive behavior (personality traits and problem behaviors) in 59 Dutch female offenders (outpatients and detainees) were compared with those in 170 male offenders (outpatients and detainees) who were all convicted of a violent crime. The violent female offenders scored significantly higher on neuroticism and trait anger, and significantly lower on hostility than the male offenders; however, effect sizes were small. A subgroup of female forensic psychiatric outpatients did not differ from a subgroup of male outpatients on all measures, whereas a subgroup of female detainees scored significantly higher on anger and aggression, but lower on hostility and psychopathy than did a subgroup of male detainees. These first results might indicate that violent female offenders do not differ much from violent male offenders regarding personality traits and problem behaviors. The differences between both groups of violent offenders were largely borne by the subgroup of violent female detainees compared with the subgroup of violent male detainees.