We tested the hypothesis that in patients with preterm premature rupture of membranes the presence of Chlamydia trachomatis in the cervix shortens the latent period (time from rupture of membranes to delivery) and increases the incidence of chorioamnionitis and early endometritis. A total of 178 conservatively managed patients with PROM between 22 and 35 weeks' gestation had cervical cultures for chlamydia, group B Streptococcus (GBS) and Neisseria gonorrhoeae performed at the time of rupture. Patients with GBS and gonorrhea were treated at the time the culture results were available and excluded from analysis. The remaining patients were divided into group 1: 26 patients (14.6%) positive for only chlamydia (and not treated until discharge from the hospital); group 2: 120 patients (67.4%) negative for all three organisms. The two groups did not differ in cesarean rate, duration of conservative management, hospital stay, or birthweight. Furthermore, the rates of chorioamnionitis (30.8% group 1; 38.3% group 2) or early endometritis (11.5% group 1; 20.8% group 2) were similar. We conclude that in patients with preterm premature rupture of membranes, the presence of chlamydia in the cervix appears to neither decrease the latent period nor increase the incidence of chorioamnionitis and early endometritis.