Objective ¿ To estimate the prevalence of Chlamydia trachomatis (Ct) among young women seeking care at family planning and education centers (CPEF) in Seine-Saint-Denis and to evaluate vulvar self-swabbing as a sampling method. Method ¿ PCR screening using self-collected samples was offered to all patients under the age of 26. Results ¿ 546 patients were included, with an overall prevalence of 11.2% [95% CI: 8.7–14.2]. Neither age, reason for consultation, nor the presence of symptoms was significantly associated with Ct carriage. Conclusion ¿ Self-collection is a well-accepted screening method. The high prevalence of infection and the young age of the patients (10.6% of whom are under 16) highlight the vulnerability of young girls seeking care at the CPEFs in the 93rd department. (R.A.)