OBJECTIVE: This study examined differences in factors associated with violence toward others by female and male patients evaluated in a psychiatric emergency service. METHODS: A sample of 812 psychiatric patients recruited in the emergency service of an urban psychiatric hospital were followed in the community over a six-month period. Patients provided self-reports of violent incidents, and collateral informants also provided reports of the incidents. Official records were also reviewed. During the followup period, 369 patients (213 male and 156 female patients) engaged in violence, defined as laying hands on another person in a threatening manner or threatening another person with a weapon. RESULTS: Male and female patients did not differ significantly in frequency and seriousness of violence, but they did differ on who the co-combatant was and where the incident took place. CONCLUSIONS: Gender is not a strong predictor of involvement in violence by psychiatric patients. The observed gender differences in location in which violence took place and identity of the co-combatant may be related to differences in the social worlds of men and women, with men having more opportunity for public violence with strangers.