1. From 1987 to 1989 in Ontario, Canada, there were 100 or more allowed workers' compensation claims among nurses for injuries due to violence. The annual rates for such claims were higher among male nurses (13.9 per 1000) than among female nurses (1.4 per 1000). 2. Compared to the general Ontario work force, the rates for such claims were significantly higher among both male and female nurses. 3. These compensation data are consistent with surveys showing that nurses and other health care workers are at risk for violent injury in the workplace. 4. The compensation data likely underestimate the extent of the problem, because no statistics are available for denied claims or claims with no lost time, and many assaults are unreported. Measures for prevention and increasing awareness are required.