We evaluated a rapid antigen detection method with an immunochromatographic assay for Neisseria gonorrhoeae (NOW Gonorrhea Test) by using urine samples from patients with urethritis to diagnose gonococcal infection in males. Among 58 male patients who underwent urethral swab culture, 34 cases (58.6%) were found to have N. gonorrhoeae infection. The sensitivity and specificity of the NOW Test compared with the results of standard culture were 94.1% (32/34) and 95.8% (23/24), respectively. The predictive values of positive NOW and negative NOW were 96.9% (32/33) and 92.0% (23/25), respectively. The detection limit of this assay was determined as 5 x 10(4) cfu/ml using N. gonorrhoeae suspension as an antigen. In contrast to standard cultures, gonococcal antigens in specimens were still detectable by this method up to 45 h of storage at either room temperature or 4 degrees C. Considering the rapidity and ease of this method, our results suggest that the NOW method might be a useful and reliable diagnostic screening tool for gonococcal urethritis.