In summer 2001, visitors to a wildlife park in Norfolk, uk, became infected with verocytotoxin-producing Escherichia coli (vtec) O157, which was associated with wild rabbit faeces. The rabbits lived in an adjacent field together with E coli O157-positive cattle. A pilot study was therefore performed to investigate the factors affecting the association between E coli O157-positive cattle and wild rabbits. Samples of faeces were taken from 16 herds of cattle that lived close to populations of wild rabbits. Analysis by culture and pcr showed that seven of the herds were positive for E coli O157. Faeces were collected from individual rabbits at six of these farms during late winter, when there were few rabbits, and during high summer, when there were many. None of the 32 samples collected on two farms in late winter was positive for E coli O157, but eight of 97 samples collected in summer were positive on four of the six farms. pcr analysis for vtec, including non-O157, showed that 20 of the 97 samples were positive.