This article explores the role ofparticipant-observation and ethnographic writing inthe shaping of medical practice since Hippocrates. Drawing on a range of historical sources and genresthat include the 17th- and 18th-centurymedical topographies and medical geographies,19th-century medical ethnography and folklore,and their marginal persistence into the 20thcentury in the form of Mexican pasante reports,I argue that these writings should not be approachedas part of the history of anthropology, but asspecifically medical genres related to medicalpractice. The abandonment of these ethnographicpractices by modern biomedicine is, I conclude, aconsequence of two related developments: the hegemonyof clinical epistemology and the depersonalization anddepoliticization of physicians'' commitment to theirpatients.