In studies of the cause of gastrointestinal symptoms in homosexual men, Campylobacter jejuni was recovered from 10 of 158 men with, and 2 of 75 men without, intestinal symptoms. In addition, a heterogeneous group of Campylobacter-like organisms was identified in 26 symptomatic and 6 asymptomatic homosexual men, but in none of 150 heterosexual men and women. Infections with Campylobacter-like organisms, like infections with C. jejuni, were significantly associated with the sexual practice of anilinctus and were usually associated with diarrhea, abdominal cramps, and hematochezia; proctocolitis seen at sigmoidoscopy; increased numbers of leukocytes seen on rectal smears; acute inflammatory changes seen on rectal biopsy specimens; and a serum antibody response to the infecting organism.