Though scorned by official medicine, alternative medicine has gained its place in the public. Where does its popularity originate from? Many studies attribute the success of alternative medicine to the role played by trust and conviction in the process of healing. If alternative medicine is a cure to many ills, this is because of an illusion shared by both the patient and the therapist. This shared illusion is at the basis of the placebo effect , the source of alternative medicine s surprising success. J.-J. Aulas presents one of the first complete and objective evaluations of alternative medicine s current popularity.