Mycobacterial infections of marsupials are important for two reasons. Firstly, the Australian brushtail possum (Trichosurus vulpecula) serves as the major wildlife reservoir for Mycobacterium bovis in New Zealand and secondly, M. avium is a significant cause of disease in endangered marsupial species held in captivity. Marsupials are highly susceptible to specific mycobacterial infections which may be linked to deficiencies in their cellular immunity. Histopathological inspection of affected tissues indicates that, unlike most eutherians, marsupials are unable to wall off infection sites, resulting in formation of satellite lesions and generalised disease. This review examines possible reasons for the high susceptibility of marsupials to mycobacterial infections and investigates the prospects for developing vaccines to control these diseases.