Anthropological research on biomedicine voices patient perspectives of medical encounters and describes biomedicine as a cultural, historical construct. It reveals sociocultural particularities of biomedicine obscured by the illusion of objective, rational, and natural reality, or a so-called “aura of factuality”(Geertz 1973, Rhodes 1996). Uncertainty and discomfort arise for patients facing culturally-specific models of illness and healing considered acultural by biomedical discourse.Medical anthropologists have long described biomedicine as a socioculturally-embedded site of social control, reflective and reproductive of broader social priorities such as depersonalized capitalist efficiency, power-reinforcing hierarchy, commodification of bodies, neoliberal individualism, alienation of body and mind, etc. (Foucault 1975, Baer et. al 1986, Martin 1987, Scheper-Hughes and Lock 1987, Kleinmann 1988). Others have depicted the biomedical clinic as a culturally unique space that breaks otherwise ubiquitous norms—for example, giving a near-stranger (a doctor) unprecedented physical access and knowledge of one’s body—and requires re-socialization for its participants (healers and patients) to accept unique social rules (Taussig 1980, Konner 1987, Good 1994). Biomedicine as a system of knowledge and practice thus has a special role of both breaking and reinforcing social codes. Biomedicine is a socially distinct structure that presents itself as natural and consistent with the rest of society, by way of justification through scientific rationality and mirroring of other societal power structures—ultimately creating ambiguities and confusion for the seriously sick seeking biomedical care.This is not to strictly distinguish biomedicine as confined to the clinic, or to depict it as a distinctly bordered institution ready for the sick to enter—on the contrary, biomedicine’s explanatory models pervade everyday consciousness in the Western world. As Baer et al. (1986) write, “the dominant ideological and social patterns in medical care are intimately related to hegemonic ideologies and patterns outside of medicine”(95). This makes it difficult to epistemologically disentangle the biomedical domain from the rest of society.Nonetheless, from a patient’s perspective, there is a distinct social territory, or a “sick world” for the seriously sick who seek biomedical treatment. As Sontag (1978) puts it, “everyone who is born holds dual citizenship, in the kingdom of the well and in the kingdom of the sick” and “the patient enters a duplicate world with special rules”(35). This territory consists not only of distinct metaphors and social rules (Sontag’s focus), but also patients, caregivers, institutions, and treatment processes. It structures power and knowledge regarding the body (most of which is allocated with physicians), and upon entry requires a type of socialization, or education in new social norms. For the physician or the anthropologist, biomedicine may represent an omnipresent cultural explanatory system—but for many patients, the mentally transformative and absorptive qualities of the institutions one enters during illness are equally relevant due to the uncertainty they cause and the mental work they require for entry.This essay distinguishes the “healthy world” from the “sick world” to point out the distinct learning process required of the sick in order to fully engage with the new norms in the process of biomedical care—a transition that often results in uncertainty for patients. Rather than consider biomedicine as an “intervention” that imposes on sickness and life, this essay, and the patients interviewed for it, more closely describes a model of entrance into biomedical care as a semi-encompassing “sick world” with its own culture.