Background: Population aging places greater demands on the supply of informal carers. The aims of this study were to examine (1) the types of unmet support needs of carers of older Australians and (2) the association of unmet needs with mental health.; Methods: Utilizing new data from the 2015 Australian Bureau of Statistics (ABS) Survey of Disability, Ageing and Carers, we calculated the prevalence of carers experiencing specific and multiple unmet needs for support, using single and multiple item measures. Logistic regression models were fitted to examine the association between unmet needs and psychological distress (using the Kessler psychological distress scale), once demographic and health factors were controlled for.; Results: In 2015, 35% of carers of older Australians cited at least one unmet need for support. Among this group, almost two-thirds cited multiple unmet support needs (64.7%). The most prevalent types of unmet needs included financial (18%), physical (13%), and emotional support (12%), as well as additional respite care and support to improve carer health (12%). After controlling for demographic and health characteristics of the carer, having any unmet need for support increased the odds of psychological distress by twofold (OR = 2.20, 95% CI = 1.65, 2.94). With each successive unmet need for support, the odds of psychological distress increased 1.37 times (OR = 1.36, 95% CI = 1.22, 1.54). Those who had received assistance with care, but required further support were 1.95 times more likely (OR = 1.95, 95% CI = 1.17, 3.24) to be in distress and those who had not received care assistance were about 2.4 times more likely (OR = 2.38 95% OR = 1.56, 3.62) to be in distress relative to those with no unmet need.; Conclusions: Addressing unmet support needs of carers is important, not only for the planning of services for carers in an aging population, but also because of the association between unmet support needs and carers mental health.