Russia and Eastern Europe have the fastest growing HIV epidemic in the world. As sexually transmitted infections (STIs) play an important role in HIV transmission, we conducted this study to find the prevalence of three microorganisms associated with STIs in Arkhangelsk Oblast, Russia. First void urine from 1729 participants was analysed using nucleic acid amplification testing, and all participants completed a questionnaire. One hundred and twelve (6.5%) were tested positive for Chlamydia trachomatis, 67 (3.9%) for Mycoplasma genitalium and 221 (12.8%) for Ureaplasma urealyticum. A significant association was found between C. trachomatis and U. urealyticum (odds ratio [OR] 1.85; 95% confidence interval [CI] 1.1 to 3.0). U. urealyticum was associated with similar social demographics and sexual risks as C. trachomatis and M. genitalium. This suggests that U. urealyticum has a possible role as an STI pathogen or might be a contributing factor for the spread of other STIs.