SUMMARYMycoplasmainfections are most frequently associated with disease in the urogenital or respiratory tracts and, in most cases, mycoplasmas infect the host persistently. In HIV-infected individuals the prevalence and role of genital mycoplasmas has not been well studied. To investigate the six species ofMycoplasmaand the risk factors for infection in Jiangsu province, first-void urine and venous blood samples were collected and epidemiological questionnaires were administered after informed consent. A total of 1541 HIV/AIDS patients were recruited in this study. The overall infection rates of sixMycoplasmaspecies were:Ureaplasma urealyticum(26·7%),Mycoplasma hominis(25·3%),M. fermentans(5·1%),M. genitalium(20·1%),M. penetrans(1·6%) andM. pirum(15·4%). TheMycoplasmainfection rate in the unmarried group was lower than that of the married, divorced and widowed groups [adjusted odds ratio (aOR) 1·432, 95% confidence interval (CI) 1·077–1·904,P< 0·05]. The patients who refused highly active antiretroviral therapy (HAART) had a much higher risk ofMucoplasmainfection (aOR 1·357, 95% CI 1·097–1·679,P< 0·05). Otherwise, a high CD4+T cell count was a protective factor againstMycoplasmainfection (aOR 0·576, 95% CI 0·460–0·719,P< 0·05). Further research will be required to confirm a causal relationship and to identify risk factors forMycoplasmainfection in HIV/AIDS populations.