Hemodialysis is a relatively new palliative treatment which extends the life of those with chronic, terminal renal failure. Patients undergo three weekly sessions of extra-renal purification, as long as they have not undergone a transplant. In this project, undertaken in the course of a licence and diploma in health, I examined the life trajectory and identity of these patients, looking particularly at the processes by which they become “hemodialyzed,” described by the treatment they are undergoing. I decided on a sociological approach, carrying out a comparative analysis of two hemodialysis centers. Patients’ trajectories are defined by a multi-stage process: the initial shock is followed by adaptation, and encourages the emergence of a lay knowledge which may or may not be recognized by professionals, depending on the center. The technique also structures patients’ identity processes, which are marked by signs of having entered into a deviant or stigmatized path, signs which help construct an individual identity—that is, an identity defined by the lack of any specific identity. This deficit may explain the demand for training and the development of technical ability among some patients during the time they spend in centers where hemodialysis is heavily used. Acknowledging the patient as an actor in the care process, just like the medical staff, redefines the place of nurses, who may find benefits for their professional identity.