The prevalence of infections caused by Mycobacterium bovis was estimated in two populations of wild animals in the south west of England. A variety of mammalian species was trapped on farm land where incidents of infection with tuberculosis had occurred in cattle. Bacteriological analysis of lymph node samples and lesions showed that the only animals acting as a reservoir for M. bovis were badgers. Examination of arthropod ectoparasites of infected badgers proved negative for M. bovis and suggests that these are unlikely to act as vectors in transmission of the disease.