One of three feral rabbits from a colony on a hill grazing used to sustain farmed red deer in north-east Scotland, had chronic intestinal lesions resembling paratuberculosis (Johne's disease), but similar lesions were not found in 29 juvenile and adult rabbits killed subsequently on the same ground. Acid- and alcohol-fast bacteria were observed in fixed tissues, but material for culture was not obtained from the affected rabbit, thus the species of Mycobacterium involved was not identified. The farmed deer had experienced recently a severe outbreak of paratuberculosis.