Objective: The aim of this study was to identify and describe the circumstances of homicides that have occurred in inpatient psychiatric facilities in Australia and New Zealand in the past 25 years. Methods: Homicides in psychiatric hospitals were identified by an acquaintance chain method. Results: Eleven homicides by ten patients occurred within psychiatric hospital wards in Australia and New Zealand between 1985 and 2010. The homicides fell into three broad categories: homicides by acutely ill patients soon after admission, homicides by forensic patients in low-security settings, and homicides in which vulnerable and elderly patients were victims. Conclusions: Acute psychiatric units should have adequate procedures for controlling acutely ill and physically menacing patients. It is also recommended that patients who have committed serious violence in response to symptoms during previous episodes of illness be treated with an adequate dose of antipsychotic medication. An important task in any psychiatric hospital is to protect patients and staff from physical violence.