This review examines the current state of knowledge of aspects of tuberculosis in the badger. The gross pathology and pathogenesis are elaborated as well as the immune mechanism, diagnosis of infection and excretion and viability of infected products. The epidemiology in badgers is considered, as is the significance of infection in this species for other wildlife species as well as domestic animals sharing the same habitat. Trials of the effects of the removal of badgers on the occurrence of tuberculosis in cattle are summarised. It is concluded that badgers are well adapted as the primary host of bovine tuberculosis in parts of Britain and much of Ireland. Copyright 2000 Harcourt Publishers Ltd.