Aim. To assess the prevalence of HIV, syphilis and hepatitis C in prisons in the Republic of Tajikistan.Materials and methods. The biobehavioural study included anonymous testing for 3 infections (HIV, syphilis and hepatitis C) and a survey. Participation was voluntary. Each participant was able to access the results of the study through their unique code, which was assigned prior to the start of the study. Data entry and analysis were performed using Epi-Info-3.5.2 analysis software.Results and discussion. The prevalence rates of HIV, syphilis and hepatitis C in prisons were HIV - 3.4%, syphilis - 2.8%, hepatitis C - 8.9%. According to the results, drug use by injection is prevalent in prisons. The presence of homosexual contacts in prisons is also confirmed.Conclusion. HIV prevalence among prisoners in Dushanbe has increased from 2.2 to 2.9 per cent. In Dushanbe, it increased from 2.5 per cent in 2020 to 3.5 per cent in 2023, while in Khujand it decreased (3.8 per cent and 3.3 per cent). Prisoners’ awareness of HIV/AIDS and use of preventive measures is low. In 2023, only 56 per cent of prisoners had been tested for HIV.