Cervical cancer continues to be an important public health problem in Thailand. While the high risk humanpapillomavirus (HPV) types have been established as the principle causative agent of both malignancies andthe precursor lesions, cervical intraepithelial neoplasia (CIN), other factors may also be involved like othersexually transmitted diseases, as well as smoking. Chlamydia trachomatis is an obligate intracellular Gramnegativebacterium which has a tendency to cause chronic infection featuring inflammation and therefore mightbe expected to increase the risk of cervical cancer. In the present nested case-control study, 61 cases of cervicalcancer and 288 matched controls with original serum samples were identified from the Khon Kaen Cohort,established in the North-East of Thailand, by linkage to the Khon Kaen population based cancer registry. C.trachomatis specific IgG antibodies at recruitment were measured by microimmunofluorescence and assessed forassociation with cervical cancer using STATA release10. No significant link was noted either with all cancers orafter removal of adenocarcinomas. The results suggest no association between Chlamydia infection and cervicalcancer development in North-East Thailand, but possible influencing factors must be considered in any futureresearch on this topic.