Worldwide, Mycoplasma genitalium (MG) is increasingly reported as an emerging cause of sexually transmitted infections. Internationally, the prevalence of MG is higher in male with urethritis and community groups especially among people living with HIV (PLHIV). While MG is treatable, antimicrobial resistance is a rising concern. This cross-sectional study aims to determine the prevalence of MG infection and the antimicrobial resistance pattern in HIV-infected male in Hong Kong. A total of 750 HIV-infected male attending HIV specialist clinic in Hong Kong would be recruited. The main outcome measures include prevalence of MG and resistance mutations to macrolide/fluoroquinolone in HIV-infected male; prevalence of MG/STI co-infections, as defined by concurrent detection of MG and one or more other bacterial STI.