We investigate the role of preferences for risk on health and sexual behaviours of 805 female sex workers in Senegal, of whom 441 were surveyed twice at a two-year interval. Risk preferences were measured using simple incentivised risk elicitation tasks as well as domain specific risk-taking scales. We find that the experimental measure was poorly correlated with self-reported measures. We further find that risk preferences were highly stable across domains and fairly stable over time. Our main result indicates that risk preferences measured in the lab are a main predictor of sex workers’ health and behaviours. We find that risk averse sex workers demand more preventive services and are less likely to engage in risky sex and, as a result, are less likely to be infected with sexually transmitted infections, including HIV/AIDS. Hence, our results conrm the role of risk preferences in the spread of HIV/AIDS epidemic.