In this paper, we present a simple theoretical model to investigate how economic development affects AIDS epidemics through its influence on individuals’ sexual behavior, building on the literature on economic growth with endogenous mortality concern. We employ provincial data from China on the incidence rate of AIDS between 2002 and 2008 to test the theoretical predictions. The findings are: (1) a rise in personal income/wealth induces more safe sexual activities and reduces the prevalence of AIDS; and (2) increases in public health expenditure do not have a significant positive impact on individuals’ preference of risky sexual activity over safe sexual activity.