Hematology and serum biochemistry blood values are tabulated for Australia's most critically endangered mammal, the Gilbert's potoroo (Potorous gilbertii). Significant differences were found between origin (captive or wild individuals) and age (subadult or adult) of animals. Sex, and presence or absence of Treponema infection, had minimal significance on blood values. Typical cell morphology is discussed, and hemoparasite examination identified Theileria spp. and Breinlia spp. Eighty samples were collected from a population of only 35 individuals, reflective of a population census rather than of a study reliant on statistical extrapolation. These reference ranges and findings will assist in the ongoing health management of this critically endangered species.