The locked-in syndrome (LiS) was broken down on the basis of neurological symptoms in 12 patients. The criteria of classical LiS are total immobility except for vertical eye movements and blinking. If any other movements are present one should consider the condition as incomplete LiS. Total immobility, including all eye movements, combined with signs of undisturbed cortical function in the EEG led to the concept of total LiS. The anatomical basis for this condition consists of lesions in both cerebral peduncles which interrupt the pyramidal and corticobulbar tracts, the supranuclear fibers for horizontal gaze and the postnuclear oculomotor fibers. As to the course, chronic and transient LiS have been described.