An outbreak of gastroenteritis caused by campylobacter infection was identified in May 1995 in a residential school in Gloucestershire for children with special needs. Eight primary and four secondary cases were identified, mostly confined to one house in the school; faecal specimens from three cases grew Campylobacter jejuni. A retrospective cohort study showed that drinking pasteurised milk from bottles with damaged tops was associated with illness in primary cases (p = 0.01). Bird pecking of milk bottle tops probably accounts for several thousand cases of human campylobacter infections during May and June each year in England and Wales. Milk bottle containers for doorstep delivery should be resistant to contamination by birds.