In 1979 the Belmont Report warned about threat of “undue influence” on the ability of potential research participants to provide voluntary informed consent. The authors defined undue influence as, “an offer of an excessive, unwarranted, inappropriate or improper reward or other overture in order to obtain compliance.” The attention levied on undue influence has had profound and lasting effects on the way that individuals are recruited and compensated for their participation in research. In this paper I will describe the theoretical foundations of undue influence and argue that the concept is fundamentally flawed. Furthermore, I will provide a defense of why ethics review committees (ERCs) and institutional review boards (IRBs) should not consider undue influence in their assessment of research proposals. Lastly, I will argue that a focus on undue influence by ERCs and IRBs raises the real prospect of exploitation and discrimination of potentially vulnerable groups.