Introduction: Chlamydia trachomatis infection is among the STDs that are known to increase the risk of HIV infection. The present study aims to determine the seroprevalence of C. trachomatis among HIV positive women in Ilorin and Offa, Kwara State, North Central Nigeria. Methods: Serum samples from 400 HIV positive women attending the HAART Clinic in Offa and the Ilorin General Hospital in Kwara State, Nigeria, were screened using Enzyme Linked Immunosorbent Assay (ELISA), utilizing the immunocomb Chlamydia IgG test kit (Calbiotech, El Cajon, CA, USA) to check for the existence of anti-C. trachomatis antibodies. Result: Anti-C. trachomatis antibodies were present in 92 (23.0%) of the 400 HIV positive women samples. There was a higher prevalence among the age group 36-40 years. Hence, age groupings were statistically and significantly associated (p=0.001) with the seroprevalence of C. trachomatis among HIV positive women. Married HIV positive women (60.9%) had the highest prevalence of C. trachomatis, with a statistically significant association (p=0.001). There was a statistically significant association between the number of sexual partner(s) (p=0.001) and the seroprevalence of C. trachomatis among HIV positive women. Conclusions: The high frequency confirms the necessity for comprehensive sexual education among young adults and routine testing for anti-C. trachomatis. It reflects the endemicity of the infection in Ilorin and