Objectives: To determine the effects of risk and payment on subjects’ willingness to participate, and to examine how payment influences subjects’ potential behaviours and risk evaluations.Methods: A 3 × 3 , between subjects, completely randomised factorial design was used. Students enrolled at one of five US pharmacy schools read a recruitment notice and informed consent form for a hypothetical study, and completed a questionnaire. Risk level was manipulated using recruitment notices and informed consent documents from hypothetical biomedical research projects. Payment (...) levels were determined using the payment models evaluated by Dickert and Grady as a guide. Five dependent variables were assessed in the questionnaire: willingness to participate, willingness to participate with no payment, propensity to neglect to tell about restricted activities, propensity to neglect to tell about negative effects, and risk rating.Results: Monetary payment had positive effects on respondents’ willingness to participate in research, regardless of the level of risk. However, higher monetary payments did not appear to blind respondents to the risks of a study. Payment had some influence on respondents’ potential behaviours regarding concealing information about restricted activities. However, payment did not appear to have a significant effect on respondents’ propensity to neglect to tell researchers about negative effects.Conclusions: Monetary payments appear to do what they are intended to do: make subjects more willing to participate in research. Concerns about payments blinding subjects to risks could not be substantiated in the present study. However, the findings do raise other concerns—notably the potential for payments to diminish the integrity of a study’s findings. Future research is critical to make sound decisions about the payment of research subjects. (shrink)