First-void urine specimens from 224 male recruits and 443 patients of venereal disease clinics without complaints of symptoms of urethritis were collected. Urinary leukocyte esterase test, two enzyme immunoassays (EIAs: Syva MicroTrak and Orion), a chemiluminometric assay (Magic Lite) and Syva's MicroTrak direct immunofluorescence test were used. The prevalence of chlamydial urethritis in the study population as determined by direct immunofluorescence test of first-void urine in the military recruits and venereal disease patients was 1.3% and 6.3%, respectively. The denominator used for calculation of sensitivities was the sum of patients with positive test results in at least two of the different test systems used. The sensitivities of first-void urine were 100% for Syva EIA, 96.7% for Orion EIA and 86.7% for the chemiluminometric assay. All assays proved highly specific (99.5-99.7%). Compared with direct immunofluorescence test of first-void urine, the urine leukocyte esterase test had a sensitivity of 93.6% and a specificity of 94.3%. The study showed that the urine leukocyte esterase test is an effective method to detect males infected by Chlamydia trachomatis.