Despite the rising number of cases of HIV in adults over age 50, older persons rarely are considered to be at risk for HIV/AIDS, and even though they may be involved in risky behavior, such as unprotected penetrative sex, they may not consider themselves vulnerable to becoming infected. Informed awareness of risk is essential to making positive decisions about adopting preventive measures. We examined demographic, sociobehavioral, and contextual factors that predict urban, low-income older adults' perception of HIV/AIDS risk. Logistic regression results from 398 residents aged 50-93 living in six buildings in two American cities found that males, younger participants (aged 50-61), those living in higher risk buildings, and those who worried more about contracting HIV/AIDS were more likely to perceive themselves to be at HIV/AIDS risk. Findings accounted for 32% of the variance and the prediction success rate was 72%. Results point to the importance of considering sociodemographic characteristics and environmental (contextual) factors as they influence heuristic decision making in understanding HIV/AIDS risk perception among low-income urban older adults and when designing HIV/AIDS education and intervention strategies targeting this population.