Objective: The objective of this study was to explore the prevalence of C. trachomatis infections in the pharynx of patients attending a clinic for sexually transmitted infections, and determine whether orogenital sex may play a role in the transmission of genital C. trahcomatis infections. Methods: All patients were required to fill out a questionaire on sexual behavior and history when attending the clinic. Patients having had orogenital sex within the past 6 months were asked to participate in the study. Pharyngeal and anogential specimens were collected from 160 women and 1134 men having sex with men (MSM), and the results were compared to the sexual history of the patients.Results: C. trachomatis was isolated from the phaynx in 1,3% of the women and in 1,7% of the MSM, and from anogenital sites in 11,3% of the women and 10,9% of the MSM. 5% of the women and 32,7 % of the MSM with positive anogential sample reported that they used condoms consistently in every intercourse. Conclusion: Orogential sex is a potensial mode of transmission for gential C.trachomatis infection, and may contribute to the increasing prevalence of genital C.trachomatis infection in the sexually active population.