The performance of a commercial EIA (Chlamydiazyme) for detection of Chlamydia trachomatis in urine specimens was compared with that of culture of urethral samples from men with urethritis. The incidence of chlamydial infection on the basis of culture results was 34% (56/167). The sensitivity, specificity, positive and negative predictive values for the EIA were 55% (31/56), 98% (109/111), 94% (31/33) and 81% (109/134), respectively, compared with culture. Although this EIA has a high specificity, the low sensitivity makes it valueless as a clinical tool for demonstrating chlamydial antigen in urine from men with urethritis.