A prospective study of 505 unselected women presenting for induced abortion was undertaken to determine the prevalence of Chlamydia trachomatis and to determine if cervical isolation of C trachomatis before abortion increases the risk of postabortal endometritis. A comparison of direct fluorescent antibody (slide) test with tissue culture for diagnosing C trachomatis infection also was evaluated in this population. C trachomatis was identified by culture in 89 patients (17.6%) and by direct slide test in 85 patients (16.8%). Six of 17 patients with postabortal endometritis were culture positive for C trachomatis, with a significant correlation between C trachomatis infection and development of endometritis observed (P less than .05). These data suggest C trachomatis may play an important role in postabortal endometritis.