In Australia, there is a clear relationship (r=-0.56) between the ratio of health expenditure to burden and the ratio of mortality to disability across illness groups. Those illnesses with high mortality relative to disability (e.g. cancer and cardiovascular) are associated with lower health expenditure, relative to the burden they impose. Conversely, illnesses with low mortality but high disability (e.g. musculoskeletal disorders) demonstrate higher expenditure. The notable exception is mental health, which has low mortality, high disability and very low health expenditure. Indeed, the relationship between the mortality/disability and health expenditure/burden ratios is stronger (r=-0.72) when mental health is excluded. As this disparity cannot be explained by a lack of cost-effective treatments for mental disorders, we propose a process of affirmative action for mental health. Urgent investments in cost-effective modes of care are required and these should prioritise increased access among those subpopulations disadvantaged by other social, economic or geographic factors.