This cross-sectional study focused on the sexual and reproductive health of women living with HIV, by age group, in the city of Porto Alegre, Rio Grande do Sul State, Brazil. The sample consisted of 691 women. Differences were observed in number of pregnancies and number of children. History of illicit drug use was more frequent in the 18-34-year age group, and exchanging sex for money was more frequent among women 18-29 years of age. This sample of women living with HIV treated in specialized public services in Southern Brazil showed a socioeconomic profile and sexual behavior that did not match the pattern typically identified in the process of "feminization" of the epidemic (with a majority of poor women with low schooling and a limited number of sexual partners). The study provides evidence of factors characterizing women's vulnerability to HIV infection, differing by age and raising specific demands for healthcare services.