More than one-third of the terrestrial mammal species of the central deserts of Australia have vanished in the past 50 years. Few of these have been the subject of even preliminary scientific study, and data as basic as geographic range and preferred habitat are lacking for many species. Aborigines, many of whom lived traditionally in the central deserts until recently, still retain a profound knowledge of the mammals, but this knowledge, too, is fast disappearing. Aboriginal people living in communities scattered through and around the edges of the 1645 000 km2 of the study area, comprising the Great Sandy, Little Sandy, Tanami, Gibson and Great Victoria Deserts and the Central Ranges district, were shown museum skins and asked to provide information about local names, current and past status, and aspects of biology and ecology. Most species, including some thought to have become extinct early this century, persisted in the deserts until 30–50 years ago. New data are presented on former distribution and on the biology and ecology of many species. The mammal fauna of the central deserts was richer and more widespread than generally believed, but the area has suffered a massive and sudden loss of species, probably unparalleled in extent elsewhere in Australia.