Campylobacter jejuni is a major cause of human inflammatory enteritis, but colonizes the gastrointestinal tract of poultry to a high level in a commensal manner. In vitro, C. jejuni induces the production of cytokines from both human and avian-model epithelial cell and macrophage infections. This suggests that, in vivo, Campylobacter could induce proinflammatory signals in both hosts. We investigated whether a proinflammatory cytokine response can be measured in both day-of-hatch and 2-week-old Light Sussex chickens during infection with C. jejuni. A significant induction of proinflammatory chemokine transcript was observed in birds of both ages, compared with levels in mock-infected controls. This correlated with an influx of heterophils but was not associated with any pathology. These results suggest that in poultry there may be a controlled inflammatory process during colonization.