Canada’s population grows because of and through its immigration program. But what happens for people with HIV who apply to settle permanently? The immigration system – a core social institution in Canada – includes mandatory HIV screening within a medical inadmissibility regime designed to exclude people with HIV. This is a narrative-driven analysis of the medico-legal and administrative practices governing immigration to Canada. Following the sequence of events in the application process of a woman from sub-Saharan Africa in her interactions with an immigration doctor of western European descent, Screening Out is an institutional ethnographic mapping of the Canadian immigration process from the perspective of the very people to whom the exclusionary health policy is directed. As Laura Bisaillon demonstrates, mandatory HIV screening triggers institutional practices that are highly problematic not only for would-be immigrants, but also for those bureaucrats, doctors, lawyers, and other actors who work for and within the Canadian immigration system. She provides a vital corrective to state claims about the functioning of – and the professional and administrative practices supporting – mandatory HIV testing and medical examination, showing how and where things need to change.