Forty-six psychiatric residents at a county hospital were surveyed about their exposure to patient violence. The overall incidence of assaults was 2.8 per 100 resident-months at risk. Statistically significant differences were found in the rates of assaults on different services; the rates were highest on the child and adolescent services and lowest on the adult outpatient service. Most of the assaults were committed by psychotic, male, young adults, but only male sex and age less than 13 years were statistically associated with increased risk of assaultiveness. Diagnosis and race were not associated with assaultiveness. The usual means of attack involved hitting or kicking and seldom resulted in serious injury.