Although taken for granted today by people and by some experts, the unconscious has never been experimentally demonstrated. Even for the psychoanalysts, the unconscious is nothing more than a model. The unconscious, if anything, is normally obscured by conscious activities and can only express itself in response to conditions leading to non-ordinary mental expressions, for instance during hypnosis. For many years, we have been using hypnosis in variegating experimental setting, and we think one of the evidences coming from our tests is the experimental demonstration that the unconscious exists and can be forced to respond to solicitations the participant is not aware of. We administered hypnotic suggestions to highly-hypnotizable normal participants with the aim of inducing hallucination of body heating, alexia, amusia, spatial neglect, focused analgesia, general anaesthesia, and age regression. Following such suggestions, participants actually experienced a sensation of heat, incapability to read, lack of interest in a side of the world, indifference to painful stimuli, and revivification of infantile age, respectively. But this is not all. Through the above-mentioned suggestions we also obtained some physical reactions that could only be defined as unconscious, i.e. increase of the stroke volume and of the mesenteric artery flow following hallucinated body heating, reduction of reaction times to incongruent color words in a Stroop task following alexia, prolongation of ipsilateral reaction times following spatial neglect, reduction of mismatch negativity to deviant stimuli following hypnotic amusia, coherent modifications of the sympathetic/parasympathetic balance to trigeminal and non-trigeminal pain during analgesia and anaesthesia, reduction of Raven score and Raven-induced stress during age regression. These responses evoked during hypnosis in response to mental images are clearly non-voluntary and non-conscious, and demonstrate in experimental setting with the tools that are typical of human physiology—the existence of unconscious to perceive and react.