We report on five years' experience of staff injuries from patient attack in a large state hospital. In 1984 to 1988, with a total of 6,225 staff person-years of exposure, 209 employees suffered 236 injuries from patient attack. Ward nursing staff sustained 185 of the injuries (5.7 injuries per hundred person-years), professional staff 17 (rate = 2.3), psychiatric technician trainees 27 (rate = 6.2), and nonclinical staff 7 (rate = 0.4). The annual rate of injury by attack was 50 percent higher among male nursing staff (6.9 injuries per hundred) than among females (4.5). The annual rate of injury by attack was slightly higher among psychiatrists (6.0 per hundred person-years) than among nursing staff. Two three-hour peak periods for injury from patient attack were identified: 8:00 am to 10:59 am and 4:00 pm to 6:59 pm. These six hours accounted for half the injuries. We observed more injuries on Mondays and Tuesdays (42.5 per day), compared with the rest of the week (30.4 per day). No difference in staff injuries was noted between Wednesday-Thursday-Friday and weekend days; 74 percent of staff injuries from attack occurred on the victim's own ward; 70.7 percent of injuries from patient attack were head injuries.