What is the value of medical research? The question initially provokes an ethical response: the worth of a clinical trial is generally understood in terms of the impact of its outcomes on patient populations. The evaluation of human subjects research raises normative questions of values – the future well-being of society in relation to the risk experimental procedures entail for participants. However, biomedical facts also circulate within national systems of healthcare, global policy organizations, property regimes and pharmaceutical markets. The current dominance of public-private partnerships under the rubric of ‘global health’, the uptake of pro-market strategies by governmental and philanthropic organizations, the bankrolling of the WHO by private individuals, suggest the extent to which the value of both therapeutic products and public health practices have been appropriated by a logic of profit. Clinical trials engage with and generate multiple orders of value; they straddle the world of commodities and public goods, of fiscal costs and moral virtues (Stark 2009). The papers in this special issue probe the different systems of value that exist between scientific ends, public goods, and lucrative commodities. Taking inspiration from recent ethnographic studies of finance in practice (e.g. Roitman 2005) and economic sociology (e.g. Caliskan & Callon 2009), they explore how value is variously worked through material, socio-technical relations, institutions, and research practice. To discern the value of research ethnographically, a common starting point of these papers is the work of medical research, including volunteered participation, contracted employment, scientific analysis or ethical oversight. In drawing attention to the modalities of intellectual, practical, and affective labour that drive a clinical trial, this special issue situates the production of medical knowledge with respect to other forms of productive activity. In so doing, we seek to nuance perspectives on the significance of clinical research to the welfare of societies. What follows is a selective overview of social scientific research that explores the linkages between clinical trials, pharmaceutical markets and global health inequities. We suggest that this scholarship can be roughly characterized by two distinct critical aims. The first concerns the political economy of medical research and the structural conditions under which health becomes a resource for wealth. The value of medical research is analysed through an investigation of medical markets as networks of knowledge production, therapeutic consumption, and capital accumulation. The second interrogates the ethical significance of transnational clinical experimentation. In these studies, value is elaborated as a negotiation between the interests of communities, the protocols of science, the priorities of global health; it indicates access to life saving therapies, the equitable distribution of research benefits, and the means and terms of engagement afforded by a research project. Though articulated in different registers, we suggest that both these approaches to value demarcate the ‘social’ from the ‘economic’ dimensions of clinical research. Studies that explore the sociological consequences of the commercialization of medical research and those that seek to strengthen the moral traction of experimental procedures both analyse value as a structuring and systematic logic. We take an alternative track. Concerned with how the material practices of medical research intersect with everyday ways of living, we propose a more promiscuous approach to the question of value, one that is acutely aware of the diverse valuable materials and manifold processes of valuation attendant to medical experimentation. The purpose of drawing upon categories of value theory, such as ‘labour’, ‘production’, and ‘circulation’, is to open up these variables to ethnographic scrutiny (Graeber 2001). Rather than warn against economic incursions into medical knowledge and health practice, or, alternatively, the reduction of local experience to the standards of bioethics, we hope to illuminate the array of practices, knowledges, and techniques through which the value of medical research is brought into being.