Empirical research demonstrates that patient assaults on staff are a worldwide occupational hazard. This study examined patient assailant characteristics in a 20-year longitudinal, retrospective study in one public health care system. Older male patients with schizophrenic illness and histories of violence toward others and substance use disorder and younger male/female patients with personality disorders and histories of violence toward others, personal victimization, and substance use disorder were the more frequent assailants. This was true at 10-, 15-, and 20-year periods. Specific clinical findings with regard to forensic patients, the violence triad, and victimization of women as well as methodological issues were discussed and the implications noted.