The clinical and pathological findings in a group of 260 homosexual men comprising 10% of a private proctologic practice are reviewed. A clinical pattern of anorectal and colon diseases encountered with unusual frequency in these homosexual patients is termed the gay bowel syndrome. The clinical diagnoses in decreasing order of frequency include condyloma acuminata, hemorrhoids, nonspecific proctitis, anal fistula, perirectal abscess, anal fissure, amebiasis, benign polyps, viral hepatitis, gonorrhea, syphilis, anorectal trauma and foreign bodies, shigellosis, rectal ulcers and lymphogranuloma venereum. 60 anorectal and sigmoid biopsies from 51 patients failed to disclose evidence of specific infection other than condyloma acuminata. Of 21 patients with biopsy diagnosis of nonspecific proctitis, 8 had a specific infection which was detected by other means,--5 cases of shigellosis and one case each of gonorrheal proctitis, amebiasis and lymphogranuloma venereum. In evaluating proctologic problems in the gay male, all of the known sexually transmitted diseases should be considered. Shigellosis, amebiasis and viral hepatitis should be included. Microbiological evaluation is essential. Concurrent infections with 2 or more pathogens should be anticipated. Chlamydia trachomatis, an important cause of nonspecific urethritis in the general population, is high on the list of possible causes of the nonspecific proctitis present in 31 of the 260 patients.