Factors associated with HIV co-infection in cases of acquired syphilis reported in a Reference Center for Sexually Transmitted Diseases and AIDS in the municipality of São Paulo, Brazil, 2014

to describe sociodemographic and behavioral characteristics and to identify factors associated with human immunodeficiency virus (HIV) co-infection in cases of acquired syphilis reported in a Reference Center for Sexually Transmitted Diseases (STD) and AIDS. cross-sectional study with secondary data from a Reference Center for STD and AIDS in the municipality of São Paulo, Brazil, in 2014; the Poisson regression was used to estimate prevalence ratios (PR) and 95% confidence intervals (95%CI). 648 cases of acquired syphilis were reported, and 98% were male; 88% were men who have sex with men (MSM) and 57% had HIV co-infection; male sex (PR=1.95; 95%CI 1.05;3.61) and MSM (PR=1.87; 95%CI 1.38;2.53) were factors independently associated with HIV co-infection. there was a high prevalence of HIV co-infection in the service analyzed, disproportionately affecting MSM who were notified with acquired syphilis.