On the basis of extensive review of the medical records of 253 patients hospitalized in a locked psychiatric unit, the authors found that before hospitalization, men engaged in significantly more physical attacks and fear-inducing behavior than did women. During short-term psychiatric hospitalization, although men continued to engage in more fear-inducing behavior, women engaged in proportionately more physical attacks. To control for possible confounding variables, the authors repeated the analyses after stratifying by demographic and diagnostic variables that were distributed differently among men and women. The same pattern of relationships between gender and violence was found. The authors give case examples and discuss possible explanations and implications of the findings.