In the 200 years of European settlement of New South Wales, 28 of 130 species of native mammals that were originally present in the state have disappeared. Twenty-one of these species are still extant in other states, while the other seven are extinct. Regionally, losses have been much greater on the western plains (27 species lost, representing 38 per cent of the original fauna) than on the coastal strip or in the Great Dividing Range (losses 4–15%). Losses in the west are due entirely to the catastrophic demise of marsupials (16 of the original 37 species lost) and rodents (11 of 17 species lost). Of the remaining western fauna, the platypus Ornithorhynchus anatinus, dingo Canis familiaris dingo, 16 of 21 species of marsupials and three of six species of rodents have declined in distribution since European settlement; all extant species of bats are probably stable. Twenty-eight species of native mammals are judged to be currently at risk in western New South Wales at national, state or regional levels. The feral cat Felis catus is implicated in the regional demise of up to 10 species prior to 1857. The linked activities of land clearance and pastoral activity are implicated most strongly in the subsequent extinction cascade. To redress past neglect, I suggest several priorities for action: effort should be made to compile all existing mammalian records in western New South Wales; systematic surveys should be carried out to gather ecological data and information on current status so that management priorities and actions can be identified; long-term monitoring sites should be established; and finally, in certain situations species reintroductions should be considered.