Mycoplasma genitalium (MG) is a cause of urethritis. While resistance to azithromycin is increasing, routine detection of MG is not performed in Belgium, where its prevalence is unknown. The aim of this study is to determine prevalence of MG in men with urethritis.An "in-house" amplification assay detecting MG was performed on urine of men with complaints of urethritis who consulted the emergency unit or the Sexually Transmitted Infection clinic of our public hospital in Brussels. Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) were tested on the same sample. A total of 187 men were tested. Prevalence of MG was 9% (95% Confidence Interval: 5 to 13.2%). CT was detected in 20%, NG in 22% and 56% of samples were negative for these three pathogens. Neither age, ethnic origin, sexual orientation nor HIV infection were associated with MG urethritis.M. genitalium was identified in 9% of men with complaints of urethritis indicating that amplification assay detecting MG should be implemented in routine testing for those patients.