Introduction: Chlamydia trachomatis represents a causal factor of sexually transmitted infections (STI), the course of which is frequently asymptomatic. Chronic and relapsing infections with Chlamydia trachomatis may result in a disturbed function of oviducts, resulting in infertility. Objectives: The aim of the study was to evaluate the relationship between manifestations of asymptomatic infections with Chlamydia trachomatis and infertility among Polish women. Material and Methods: The study was conducted between 2010-2013 on 543 women in two groups. Group 1 included 190 patients (aged 23-39 years), in whom control tests were performed before planned pregnancy. Group 2 included 353 patients (aged 23-39 years), suffering from infertility (no pregnancy after 12 months of regular sexual intercourse). The study included all women presenting with infertility. A smear was taken from the cervical canal and DNA of C. trachomatis was isolated and identified using nested-PCR. In the statistical analysis the Fisher’s exact test was applied. Results: Infection with C. trachomatis was detected in 18 (9.47%) controls (group 1) but as many as 81 (22.95%) patients with infertility (group 2). The obtained results were significantly different (p<0.0001) between the investigated groups. Conclusions: 1. The study indicates that chronic infection with C. trachomatis may represent a significant factor resulting in infertility of women. 2. A test for Chlamydia trachomatis infection should be routinely performed in every couple with diagnosed infertility and always before a scheduled in vitro procedure.