One hundred and thirty individuals with bacteriologically proven Campylobacter jejuni enteric infection in a single outbreak were studied. Eighty-eight patients had gastrointestinal symptoms. One probable example of reactive arthritis was found. This is a frequency similar to that found in other comparable series of Salmonella typhimurium and Shigella flexneri infections, suggesting a common pathogenesis for the reactive arthritis associated with these 3 infections.