Background: Preterm labor (PTL) is a major determinant of neonatal morbimortality with adverse consequences for health. The causes are multifactorial, with intrauterine infection probably explaining most of these outcomes. It is believed that infection with Chlamydia trachomatis (CT) is also involved in PTL. Objective: To compare the prevalence of chlamydia trachomatis cervicitis in women with preterm labor and control at term. Methods: This was a case-control study conducted at Ain Shams University Maternity Hospital. This study included 70 pregnant women with singleton fetus who attended the causality and were selected to participate in the study. They were divided into two groups, cases and control group each 35 patients. Swab was taken from endocervix and chlamydia trachomatis DNA was examined by real time polymerase chain reaction (PCR). Data were analyzed by Chi-square test. Results: The prevalence of chlamydia trachomatis cervicitis in women with preterm labor is higher than in women at term; 8 cases out of 35 (22.9%) as compared to the women in the control group which was 2 cases out of 35 (5.7%) and this difference was statistically significant using (p =0.04). Conclusion: This study proved that there is an association between chlamydia trachomatis cervicitis and preterm labor. Screening and treatment of Chlamydia trachomatis infection are recommended to decrease cases of preterm labor.