A total of 20,599 samples from 4133 slaughter groups representing about 71 million broilers slaughtered between July 1, 2001 and June 30, 2002 were tested for Campylobacter species. From each slaughter group, 40 cloacal samples and 10 samples of neck skin were taken from the carcases on the slaughter line and the samples were pooled, to a pool. Campylobacter species were detected in cloacal samples from 17 per cent of the slaughter groups and in neck skin samples from 22 per cent of the groups, and the monthly prevalence figures ranged from 6 to 32 per cent. In most of the infected groups all four pooled cloacal samples were positive, but 18 per cent of the infected groups had only one or two positive samples. More than 90 per cent of the Campylobacter-positive slaughter groups were delivered by half the producers, and one in four of the producers delivered no Campylobacter-positive slaughter groups.