Chlamydia trachomatis infection is the most common of the sexually transmitted diseases. In this study of screening for C. trachomatis infection in the Turkish female population, Chlamydia IgG enzyme immunoassay (Ch IgG EIA) was used to detect the exposure to C. trachomatis. Ch IgG EIA was studied in 469 women attending the Gynecology and Obstetrics Clinic of the University of Gazi School of Medicine. Ch IgG EIA was found positive in 35 (7.46%) blood specimens. The highest ratio of seropositivity was detected among the infertile population (11.17%).