Objectives To determine the seroprevalence of HIV, STI and related risks among men who have sex with men (MSM) in Dodoma municipality, Tanzania.

Methods A cross-sectional study using respondent-driven sampling was employed to recruit study participants aged 18 years and above. Data on sociodemographics, HIV/STI knowledge and sexual practices were collected. Blood samples were tested for HIV and selected STIs.

Results A total of 409 participants aged from 18 to 60 years took part in this study. The median age at first anal intercourse was 15 years. At last anal intercourse, 37.5% practiced receptive, 47.5% insertive and 15.0% both insertive and receptive anal intercourse. The seroprevalence of HIV, herpes simplex virus 2 (HSV-2), syphilis, hepatitis B virus and hepatitis C virus were 17.4%, 38.5%, 0.2%, 5.4% and 3.4%, respectively. A third of MSM perceived their risk for HIV to be low and this was associated with unprotected sex (adjusted OR (AOR), 4.8, 95% CI 1.8 to 10.2). HIV seropositivity was also associated with HSV-2 (AOR, 5.0, 95% CI 3.01 to 11.21); having lived outside Dodoma (AOR 1.7, 95% CI 1.1 to 6.7); age above 25 years; (AOR 2.1, 95% CI 1.7 to 3.7); sexual relationship with a woman (AOR 5.6, 95% CI 3.9 to 12.8); assuming a receptive (AOR 7.1, 95% CI 4.8 to 17.4) or receptive and insertive (AOR 4.5, 95% CI 1.9 to 11.4) position during last anal intercourse; engaging in group sex (AOR 3.1, 95% CI 1.2 to 6.1) and the use of alcohol (AOR 3.9, 95% CI 1.1 to 9.2).

Conclusions HIV prevalence among MSM is five times higher compared with men in the general population in Dodoma. Perceived risk for HIV infection was generally low and low risk perception was associated with unprotected sex. STI, bisexuality and other behavioural risk factors played an important part in HIV transmission. The findings underscore the need for intensified HIV prevention programming addressing and involving key populations in Tanzania.