Background Concurrent sexual relationships facilitate the spread of HIV infection, and sex with non-primary partners may pose particularly high risks for HIV transmission to primary partners.

Objective We examined the sexual and alcohol-related risks associated with sex partners outside of primary relationships among South African men and women in informal drinking establishments.

Methods Men (n=4959) and women (n=2367) with primary sex partners residing in a Xhosa-speaking South African township completed anonymous surveys. Logistic regressions tested associations between having outside partners and risks for sexually transmitted infections (STI)/HIV.

Results Forty-four percent of men and 26% women with primary sex partners reported also having outside sex partners in the previous month. Condom use with outside partners was inconsistent for men and women; only 19% of men and 12% of women used condoms consistently with outside sex partners. Multivariable regressions for men and women showed that having outside partners was significantly associated with having been diagnosed with an STI, consuming alcohol in greater frequency and quantity, alcohol use during sex, meeting sex partners in alcohol-serving venues, and higher rates of unprotected sex.

Conclusions Having outside sex partners was associated with multiple risk factors for HIV infection among South African shebeen patrons. Social and structural interventions that encourage condom use are needed for men and women with outside partners who patronise alcohol-serving venues.