There is strong opposition in bioethics to paying research subjects. This paper, building on earlier work, gives arguments on behalf of the permissibility of payment. It develops an analogy between payment to research subjects and payment and regulation in the labour market. Few seriously oppose payment in the labour market, and the reasons to allow payment carry over to payment to research subjects. The paper then considers and rejects an alleged disanalogy, that research is special in that it involves subjects' bodies. At greater length, it assesses the argument from the gift relationship: that the value of giving is good reason not to extend market norms into research. This argument has some force in pointing out the unattractiveness of some market motivations, but those who offer it usually overlook the coordination advantages of the market. Still, the gift relationship argument against payment has something going for it, which is more than can be said for virtually all the other major anti-payment arguments.