Misconceptions about HIV transmission and prevention may inhibit individuals' accurate assessment of their level of risk. We used venue-based sampling to conduct a cross-sectional study of heterosexually active adults (N = 1,221) within areas exhibiting high poverty and HIV/AIDS rates in Miami-Dade and Broward counties in 2007. Two logistic regression analyses identified correlates of holding inaccurate beliefs about HIV transmission and prevention. Belief in incorrect HIV prevention methods (27.2%) and modes of transmission (38.5%) was common. Having at least one incorrect prevention belief was associated with being Hispanic compared to white (non-Hispanic), being depressed, and not knowing one's HIV status. Having at least one incorrect transmission belief was associated with being younger, heavy alcohol use, being depressed, not having seen a physician in the past 12 months, and not knowing one's HIV status. Among low-income heterosexuals, HIV prevention and transmission myths are widespread. Debunking them could have HIV prevention value.