The psychodynamics underlying hypnosis are investigated. Although hypnosis is increasingly used, there has been no advance in the knowledge of its theoretical background since Freud's and Ferenczi's contributions. Hypnotism is still considered as quackery by many, and among the factors responsible for this is the attitude of those who apply it. The hypnotist still wants to be surrounded by mystery, not only in order to support the treatment, but also for subjective narcissistic reasons. The author suggests a technique which one might call 'rational' hypnosis in which the patient is given information about the basic mechanisms underlying his hypnotic state. This would amount to an analysis of the transference. The courses of two hypnotic treatments