Campylobacter has been associated with poultry for many years. It is the leading cause of bacterial foodborne illness in developed countries, with C. jejuni and C. coli being identified in most cases in humans. These two species are also found in poultry. Campylobacter is ideally suited to the poultry niche, and can grow at the higher body temperature (42C) of birds. Campylobacter has been shown to have a negative effect on the health and welfare of the birds; evidence of host adaptation and host-specific species leads us to believe that Campylobacter is more than a commensal of chickens.