Diagnosis and prevalence of persistent chlamydia infection in infertile women: tissue culture, direct antigen detection, and serology. Specimens for chlamydial culture, direct fluorescent antibody (DFA) test, two enzyme immunoassays (EIA) for antigen detection, and serum for chlamydial antibodies were collected from 256 infertile women. Specimens were taken from the tubes during tuboplasty and from the cervix and endometrium during laparoscopy or tuboplasty. Antibodies to Chlamydia trachomatis were found four times more often in patients with signs of prior pelvic inflammatory disease (PID) than in infertile women with normal pelvic findings. Only 48 (37%) of 131 patients with signs of prior PID had a history of PID. Ten or more C. trachomatis elementary bodies (EBs) per smear were found in 21 (8.2%) of 256 patients. Six patients had a positive culture or a positive antigen EIA test. All six had high numbers of EBs in the DFA test. We conclude that routine culture and EIA antigen tests detect only a minority of persistent chlamydia infections in this population, but subjective factors in the interpretation of DFA methods must be considered. 