Methods: A case control study that was conducted in the Department of Obstetrics and Gynecology at Azadi Teaching Hospital / Kirkuk-Iraq during the period of 10 months from 1st of Feb till 1st of Dec 2019. It included 86 pregnant women selected from outpatient clinic and those who were admitted to the emergency department. They were divided into two groups: Case group included 43 women diagnosed with ectopic pregnancy and control group included 43 women with early normal intra uterine pregnancies (1st trimester). Women using an intrauterine contraceptive device at the time of conception or had previous history of ectopic pregnancy, infertility, tubal surgery or smoking were excluded . After obtaining verbal consent from them five ml of venous blood was collected from all women to investigate for serum anti chlamydial IgG antibody titer.Conclusion: Higher proportion of women with ectopic pregnancy had positive anti- chlamydial antibody than those with normal pregnancy. Anti-chlamydial antibody titer may play an important role to predict the risk of ectopic pregnancy as the mean of anti-chlamydial antibody titer was significantly higher in patients who diagnosed with ectopic pregnancy than that in women with normal pregnancy regardless age, gestational age or parity.