Campylobacter fetus ss. jejuni has recently been recognised as a human enteric pathogen. Five cases of campylobacter enteritis are described. All five patients had abdominal pain and diarrhoea. Two of the five patients had bloody diarrhoea and relapses. All the patients had been in contact with young dogs which had had diarrhoea. Campylobacter fetus ss. jejuni was isolated from these dogs or from their litter-mates. Canine infection with Campylobacter fetus ss. jejuni may be an important source of infection causing diarrhoea in man.