Sexually transmitted gastrointestinal syndromes include proctitis, proctocolitis, and enteritis. These syndromes can be caused by one or multiple pathogens. Routes of sexual transmission and acquisition include unprotected anal intercourse and oral-fecal contact. Evaluation should include appropriate diagnostic procedures such as anoscopy or sigmoidoscopy, stool examination, and culture. When laboratory diagnostic capabilities are sufficient, treatment should be based on specific diagnosis. Empirical therapy for acute proctitis in persons who have recently practiced receptive anal intercourse should be chosen to treat Neisseria gonorrhoeae and Chlamydia trachomatis infections. In individuals infected with human immunodeficiency virus (HIV), other infections that are not usually sexually acquired may occur, and recurrent herpes simplex virus infections are common. The approach to gastrointestinal syndromes among HIV-infected patients, therefore, can be more comprehensive and will not be discussed in this article.