The purpose of this study is to determine the prevalence of asymptomatic male patients with urethral infections attending a government sexually transmitted infection clinic in Hong Kong and their microbiological profile. A total of 274 consecutive male patients without any symptoms for urethral infections were recruited. A questionnaire was used to record the symptoms, sexual history and demographics. Further assessment, including urethral smear for Gram stain, gonococcal culture and polymerase chain reaction (PCR) for Chlamydia trachomatis (CT), Mycoplasma genitalium (MG) and Ureaplasma urealyticum (UU) were performed. In 274 asymptomatic patients, 36 patients had non-gonococcal urethritis (NGU) and two patients had positive gonococcal culture. Among the asymptomatic patients with NGU, there were 6 (16.6%), 10 (22.8%) and five (13.9%) patients with positive PCR for CT, UU and MG, respectively. In addition, there were 14 asymptomatic patients with positive PCR for CT but without evidence of NGU. In conclusion, urethral infections were identified in a significant number of asymptomatic male patients and therefore, routine screening for this group is warranted.