Change in sexual behaviour and other social, medical, and demographic factors contribute to the prevalence of sexually transmitted infections (STIs). Objective. The objective of this study is to investigate and compare the prevalence of STIs in men having sex with men (MSM) and heterosexuals. Material and methods. A total of 62 patients were selected using questionnaire survey. Of them, 31 patients informed of being involved in sexual relations with men, and another 31 patients — in heterosexual relationships. Results. The following infections were detected in examined patients: syphilis was detected in 2 (6.5%) MSM and 2 (6.5%) heterosexuals; hepatitis B was detected in 3 (9.7%) MSM; hepatitis C was detected in 4 (12.9%) MSM; HIV infection was detected in 2 (6.5%) MSM and in none heterosexuals; venereal warts were detected in 2 (6.5%) MSM and 2 (6.5%) heterosexuals; gonorrhea was detected in 4 (12.9%) and 1 (3.2%), respectively; trichomoniasis was detected in 2 (6.5%) and 1 (3.2%), respectively; chlamydial infection was detected in 5 (16.1%) and 3 (9.7%), respectively. In MSM, STIs were detected simultaneously in the urethra and rectum in 3 (14.3%) patients, only in the urethra in 5 (23.8%) patients, and only in the rectum in 5 (23.8%) patients. Of the 8 cases of rectal localization of STIs, 1 case of proctitis, 1 case of genital warts, and 6 (75%) cases of asymptomatic course were diagnosed. Conclusion. The study showed statistically significant differences in the prevalence of STIs in MSM and heterosexuals, the prevalence of atypical localization, combined forms, and asymptomatic course of STIs in MSM.