High-risk sexual behavior by HIV-positive individuals is an important factor contributing to the spread of the HIV epidemic. We conducted a retrospective chart review to compare self-reported sexually transmitted disease (STD) risk behavior and clinic diagnoses of known HIV-positive clients attending Miami-Dade County STD clinics with those of uninfected controls. One hundred ninety-one HIV-positive clients and 191 HIV-negative controls, 130 (68.1%) men and 61 (31.9%) women, were included in the analysis. HIV-positive clients were more likely than controls to report no sexual activity in the last 2 months (odds ratio [OR] = 2.6, 95% confidence interval [CI]: 1.5-4.5) or, if active, to report condom use at last sexual intercourse (OR = 3.1, CI: 1.9-5.3). However, HIV-positive clients were more likely to be diagnosed with infectious syphilis (OR = 13.0, CI: 1.6-99.4) and/or gonorrhea (OR = 2.1, CI: 1.1-4.2) than controls. This may be a result of overreporting of condom use or sexual activity in high-risk sexual networks with inefficient use of condoms. Ongoing sexual risk behavior and access to HIV primary care are important issues in this population.