Background: Chlamydia trachomatis infection is an important preventable cause of infertility. In women, up to 70% of genital infection with Chlamydia trachomatis are asymptomatic. In the management of infertility patients, a lot of clinicians or centres do not routinely screen for Chlamydia trachomatis infection. Hence all patients being investigated for infertility may potentially be at risk of tubal blockage in addition to non-tubal factor aetiology. Those with primary tubal blockage also are at risk of worsening of the blockage. Objective: To determine if there is a relationship between IgG and IgM Chlamydia antibody testing (CAT) and tubal factor infertility. Design: It was a cross sectional descriptive study. Method: The sera of 400 consecutive consenting infertile patients presenting to the gynaecological clinic of the Ahmadu Bello University Teaching Hospital, Zaria, Northern Nigeria were tested for Chlamydia antibodies using ELISA IgG and IgM kits produced by Diagnostic Automation, Inc., 23961 Craftsman Road, Suite D/E/F, Calabasas, CA 91302, USA. Results: Up to 264 (66%) of the patients had tubal factor, 64 (16%) had uterine, 56 (14%) had ovarian, 50 (12.5%) had male while 40 (10%) had others. The causative factors were not mutually exclusive. The sero-prevalence of IgG and IgMChlamydia trachomatis amongst patients with tubal infertility were 35.6% and 35.6% respectively. There was a stronger significant relation (P = 0.008) between IgM sero-positivity which suggests recent infection and tubal infertility. The relation between IgG sero-positivity which suggest chronic infection and tubal infertility was also significant (P = 0.036) but relatively lower. Conclusion: The sero-prevalence of Chlamydia trachomatis infection, IgG and IgM was significantly higher among the sub-population with tubal infertility. Chlamydia antibody testing (CAT) has predictive value for tubal infertility.