BACKGROUND For the treatment of chlamydial cervicitis, a 7- to 14-day regimen with appropriate antibacterial agents (eg, macrolides, tetracycline, fluoroquinolones) has been recommended. Many clinicians in Japan have determined the eradication rate of cervical Chlamydia trachomatis by polymerase chain reaction (PCR) prior to 3 weeks after treatment because patients' second visit rate has been low. OBJECTIVE The aim of this study was to assess the sensitivity of PCR to detect C trachomatis at various time points after antibacterial treatment. METHODS The presence of C trachomatis was determined by PCR on days 8, 15, and 22 after the end of treatment. All patients received a 7-day course of levofloxacin 300 mg/d. RESULTS The eradication rates of cervical C trachomatis were 90.0%, 97.5%, and 100.0% on days 8, 15, and 22 after treatment, respectively. CONCLUSIONS Based on data from this study, the appropriate method and time to assess the therapeutic efficacy for chlamydial infection is PCR at 3 weeks after treatment.