Separated from mainland Australia by the Bass Strait, Tasmania has acted as an island preserve maintaining large populations of many mammalian species presently uncommon, rare, or extinct on mainland Australia. There are few studies of Tasmanian mammal distributions. Recent distributional maps, based on information from surveys and mammal specimens, allowed for an investigation of the species density distributions of the terrestrial mammals of Tasmania. Compilation of species' distributional information into species density distributions provides an overview as to which areas may provide the most significant habitat for the greatest number of species; what geographic variations may influence species distributions; and which regions remain least surveyed for mammalian species in Tasmania.