Sex and gender may play a role in the association between occupational experiences and the mental health (MH) of defence and public safety personnel. This report summarizes the findings of three studies exploring sex-based differences in MH service use between Veterans and non-Veterans in Ontario. Female Veterans had significantly higher rates of MH-related physician visits, emergency department visits and hospitalizations compared to female non-Veterans. These findings impart useful information for individuals or organizations with the ability to influence healthcare policy, planning and delivery for the Canadian defence and public safety sectors.