Medical research has been central to biomedicine in Africa for over a century, and Africa, along with other tropical areas, has been crucial to the development of medical science. At present, study populations in Africa participate in an increasing number of medical research projects and clinical trials, run by both public institutions and private companies. Global debates about the politics and ethics of this research are growing and local concerns are prompting calls for social studies of the "trial communities" produced by this scientific work. Drawing on rich, ethnographic and...