Chlamydiazyme (Abbott), an enzyme-linked immunoassay (EIA), was evaluated using cell culture on Hela 229 cells as the method of reference. Samples were acquired from 611 female and 280 male patients attending the outpatient clinic for sexually transmitted disease at the University Hospital in Rotterdam, The Netherlands. The prevalences of chlamydia culture-positive female and male patients were 7.8% and 14.4% respectively. The overall sensitivity and specificity values of the EIA were respectively 68.1% and 95.8% in the female and 92.1% and 92.0% in the male population. Samples which were culture-negative but EIA-positive were re-examined by a second direct test (IDEA; Boots Celltech). If the samples from 12 females and 11 males which were negative on culture but positive with both direct tests are considered as failures of cell culture, the sensitivity of the EIA in females almost equalled cell culture (74.6% versus 79.9%) and in males was even higher (93.9% versus 77.6%). Serotyping of the cultured strains revealed that all serovars of Chlamydia trachomatis occurring in this study could be detected by the EIA. The EIA offers a relatively simple and rapid test for diagnosis of C. trachomatis infections in high-risk populations.