This article explores the ethics of paying research participants for studies involving more than minimal risk using arguments grounded in morality, logic and pragmatism, as well as patient responses from a focused qualitative study. The authors argue that payment of research participants is ethically unacceptable. Balanced against the probability of harmful risks, guaranteed payment to participants represents excessive and undue influence and leads to commodification of human health. Patients range in their opinions on whether payment for research participation is ethical, considering issues of justice and nonmaleficence. From basic assumptions about the correlation between risks, financial need and willingness to participate in studies, the authors demonstrate that payments lead to unjustly influencing patients, especially the financially needy to participate in potentially harmful studies. Previous commentators have offered methods to regulate payment to participants, but these models do not seem feasible or ethically sound.