Following the disclosure of Mycobacterium bovis infection in badgers in East Sussex in 1976, badgers have been examined from and around farms on which cattle have become infected, but with no other attributable source of infection. These farms are confined to the downland of the south-west of the county and M. bovis has been confirmed in badger populations utilising their land. The available evidence indicates that M. bovis infection in badgers is also confined to this area. A detailed study in one area on the South Downs suggested that M. bovis is endemic in the badger population and therefore presents a continued risk for cattle occupying the area.