Campylobacter fetus ss. jejuni has recently been recognized as a human enteric pathogen. Laboratory isolation has been hindered by its fastidious nature. Methods for recovery of this organism from stool culture and a specific serologic test are described. An outbreak is reported in which three members of the same family became simultaneously ill with fever, severe abdominal cramps and diarrhea. C. fetus ss. jejuni was recovered from stool specimens from all three. A fourfold increase in serum immunoglobulin G (IgG) titer to this organism was demonstrated in each patient. All three patients had been consuming unpasteurized milk from a cow whose feces were infected with C. fetus ss. jejuni.