Should humans be used as subjects in research designed to determine the toxicity of pesticides? If so, under what conditions should they be used? If not, why not, given that human subject testing is common in research studies designed to determine the safety and efficacy of drugs? Should the EPA seek, or even accept, the results of such research in formulating the evidentiary base it uses in making decisions about pesticide registration? This article does not propose to answer these questions, but to illuminate the process by which they are addressed and offer some suggestions about how other such questions might be addressed in the future.