Disease among cetaceans is an important factor contributing to population decline. Burrunan dolphins (Tursiops australis), faced two mass mortality events due to Fresh Water Skin Disease (FWSD), decimating population numbers. It is critical to investigate the species’ immune gene repertoire as a factor inuencing disease outcomes. A key region of the genome that is targeted in conservation genetics is the Major Histocompatibility Complex (MHC), a family of adaptive immune genes. MHC genes code for a receptor that is responsible for detecting anything foreign that enters the body, like pathogens, thus diversity within these genes is directly related to immune tness. The aim of this research is to investigate the genetic diversity and signatures of selection related to the MHC in Burrunan dolphins, and to compare MHC haplotypes across disease outcomes and related taxa. This research will generate critical information contributing to the conservation and management of a highly threatened species.