Men and women who came to clinics in Boston underwent pharyngeal examinations, and pharyngeal specimens were obtained for cultures for Neisseria gonorrhoeae, Mycoplasma hominis, and Ureaplasma urealyticum. Fifty-one (4.9%) of 1,037 participants had gonococcal pharyngeal infection. M. hominis and U. urealyticum were recovered from the pharynges of 149 (14.3%) and 154 (14.8%) of 1,044 participants, respectively. The history of ever having performed fellatio was associated with pharyngeal infection with N. gonorrhoeae (P less than 0.02), M. hominis (P less than 0.05), and U. urealyticum (P less than 0.006). A history of fellatio was also associated with a history of a recent sore throat. There was, however, no association between pharyngeal infection with N. gonorrhoeae, M. hominis, or U. urealyticum and a recent sore throat. Cunnilingus was not associated with symptoms or signs or pharyngitis or with the isolation of gonococci or genital mycoplasmas from the pharynx. The pharyngitis associated with fellatio remains a microbiologic enigma.