Management of pelvic inflammatory disease (PID) and decisions about contraception are being influenced by reports that oral contraceptives decrease the risk of PID. To evaluate the validity of this association, we have examined published epidemiologic evidence and reviewed relevant information from other disciplines. Current information does not permit the generalization that oral contraceptives protect against all forms of PID. Most studies conducted (1) have been limited to hospitalized women, who represent less than 25% of all PID cases and are likely to have relatively severe forms of the disease, and (2) have failed to distinguish between gonococcal and nongonococcal PID. While oral contraceptives may provide some protection against gonococcal PID, no basis exists for assuming similar protection is provided against chlamydial PID. In fact, epidemiologic and biologic evidence suggests that infection with Chlamydia trachomatis, the leading cause of nongonococcal PID, is enhanced by oral contraceptives. We judge the conclusion that oral contraceptives protect against all PID to be premature, and urge caution in its application in health policy and clinical decisions.