Objective: Despite recognition of the extremely high rates of mental illness among custodial populations and the fact that Indigenous people represent around one-quarter of Australia's custodial population, little is known about the mental health of Aboriginal and Torres Strait Islander people in custody. Mental health is an important component of social and emotional wellbeing for Indigenous people and this paper considers current evidence regarding the mental health status of Indigenous Australians in custody. Method: A systematic review was undertaken of the quantitative literature relating to the mental health problems of Indigenous people in custody in Australia. Results: Despite high incarceration rates for Indigenous people and evidence that both mental health problems and rates of mental illness are extremely high in this group, studies in this area are few and limited in scope. Conclusion: The first step toward addressing the marked social and mental health problems for Indigenous people in custody is to systematically identify the nature and extent of these problems.