The HIV pandemic takes three forms: one purely medical, another affecting public health, and a third social form characterized by the fears it raises. Each of these forms are accompanied by specific practices of exclusion: exclusion by the health system, exclusion by prevention policies, and, finally, discrimination against those attained. Unprecedented acts of solidarity attempt to eliminate these rejection practices. But more generally, this pandemic and the reactions it engenders reveal new forms of the construction and selection of social risks. Foucault's notion of "bio-power" is well suited to these phenomena.