Campylobacter spp. are commonly isolated from commercial poultry flocks. Data from recent FSA-funded UK research indicate that approximately 60% of housed (broiler) poultry flocks are campylobacter-positive at slaughter age. This will vary from company to company and from farmer to farmer. Data suggest that this may be non-random variation, with consistent patterns observed. Evidence from companies, who collaborate with the Bristol Food Safety Group, is increasingly suggesting that some farmers find it easier to protect their birds from colonisation with Campylobacter spp than others. There are a number of possible reasons for this, which may also be interrelated.