STUDY DESIGN: A case control Study. OBJECTIVE: To determine the prevalence of Chlamydia trachomatis antibody amongst infertile women compared with pregnant controls in Garki Hospital Abuja. Secondly, to assesses the relationship between exposure to Chlamydia trachomatis infection and infertility in women. METHODOLOGY: The sample size was 162 however 157 gave informed consent therefore cases were 76 infertile patients with tubal occlusion diagnosed with hysterosalpingography and confirmed by laparoscopy to exclude cases of cornual spasms, while the 81 pregnant women were controls taken from antenatal clinic patients matched with the infertile women. Both cases and control were investigated with a study protocol which solicited information on sociodemographic variables (age, marital status, educational status and parity), sexual and reproductive risk factors including age at sexual debut, number of sexual partners, and history suggestive of previous pelvic infections. Their health seeking behaviours were also evaluated. Each patient had 5ml blood collected for serological assay for Chlamydia antibody titre. All information obtained was recorded in a data collection sheet designed for the study. The data were then fed into the computer using the Epi info 2000 programme and SPSS PC + for further analysis.