OBJECTIVE Homicide is overwhelmingly committed by men compared to women. Conservative estimates suggest that more than a third of these individuals have a treatable psychiatric disorder. These data present an opportunity to mental health clinicians to assist in the prevention of homicide by improving men's mental health. METHODS We review the current literature on men's mental health with a focus on assessing and reducing homicide risk in men with psychiatric conditions. RESULTS Bipolar disorder and schizophrenia appear to share a neural endophenotype that is a risk factor for homicide. Dual disorders, or the presence of a substance use disorder with other major mental illness, are a major risk factor for homicide in males. Dual diagnosis disorders, personality disorders and pathological traits and male depression share emotion dysregulation, irritability, and reactive aggression. Promoting physician education, addressing firearm safety, reducing the reluctance of men relative to women to engage in help-seeking behaviour, and using targeted risk interviews which integrate these data are all currently recommended. CONCLUSIONS The main focus in prevention of homicidal behaviour in males with psychiatric disorders should be to identify high risk groups, to provide adequate treatment, and to facilitate compliance with long-term treatment while considering male specific problems and needs.