Chlamydia trachomatis is a common sexually transmitted pathogen. We describe six cases of tonsillitis associated with sexually transmitted C. trachomatis infection. The organism was isolated from tonsillar crypts in all patients, and from uro-genital swabs in five of the six patients. In three partners of the patients, C. trachomatis infection of the uro-genital organ was assessed. They all had a history of orogenital sexual intercourse prior to the illness.