Interest in vector-borne zoonoses has increased during the past few years as new disease agents have been identified and old ones have re-emerged due to important changes in their ecology or epidemiology. This article reviews nonviral vector-borne zoonoses that occur in the United States and are associated with mammals and their ectoparasites. The zoonoses discussed in this review include plague, tularemia, Lyme disease, tick-borne relapsing fevers. Rocky Mountain spotted fever, rickettsialpox, louse-borne typhus, flea-borne typhus, Q fever, and human ehrlichiosis.