The advances on HIV/AIDS diagnosis and treatment have enabled people living with HIV/AIDS (PLHA) better quality of life. However, the persistence of HIV-related stigma and discrimination, and the risks triggered by HIV disclosure, may be a barrier to the sexual exercise of PLHA. We investigated the prevalence of sexual inactivity and the reasons given for it among a representative sample of women of reproductive age living with HIV/AIDS (WLWHA) in the municipality of São Paulo, Brazil. We surveyed 918 WLWHA with probability proportional to average number of visits in each of the 18 referral HIV/AIDS services. Sexual inactivity was defined as not having had vaginal sexual intercourse in the year prior to research. Statistical modeling of the factors associated with sexual inactivity was carried out by way of bivariate and multivariate analysis. In all, 22.2% (n = 200) of the women did not have sexual relations in the year prior to the interview. The majority reported a reduction in desire (64.5%) and sexual activity (68%). Among the women not in a relationship, the predictors of sexual inactivity were: being older (35-49) (ORa = 2.25); not being Catholic (ORa = 2.91); having kept the diagnosis secret from their partner (ORa = 2.45); having had up to five sexual partners throughout life (ORa = 3.81). The diagnosis of HIV seems to have more of an effect on the desire for and frequency of sexual activity than on its interruption. Sexual inactivity was influenced by the stigma of HIV/AIDS, by age, and by moral-religious values.