The prevalence of Trichomonas vaginalis, Chlamydia trachomatis, Neisseria gonorrhoeae, human papillomavirus (HPV) in Sri Lanka is not well reported; the objective of this study is to describe the prevalence of these four sexually transmitted infections among attendees of sexual health clinic in an urban setting. Vaginal swabs were collected from consenting women attending a sexual health clinic and tested for the presence of the above sexually transmitted infections using nucleic acid amplification techniques. Basic demographic details were sought from each participant (483 women of age range 14-61, median 30. years, IQR 12 years) via a research assistant-administered questionnaire. Overall, a prevalence of T. vaginalis, C. trachomatis, N. gonorrhoeae and HPV was 2.3 , (95 CI: 1.2-4.1 ), 8.2 (95 CI: 5.6-11.4 ), 7.6 (95 CI: 5.2-10.8 ), 44.4 (95 CI: 39.8-49.1 ), respectively. Among the 197 positive for HPV, HPV6 accounted for 23.1 , HPV16 (12.5 ), then HPV11, HPV66 and HPV58 were the commonest. Vaccine-related types (6/11/16/18) were detected in 59.9 of cases (95 CI: 52.7-66.8 ). The high prevalence of sexually transmitted infections (45.2 ) is a potential risk factor for an increase in HIV infections in the country and the high carriage of HPV supports the need for cervical cancer screening and prevention programmes.