Chronic intermittent bipolar electrical stimulation of the left nucleus reticulatus polaris thalami was performed in a patient in a state of subcoma due to ischaemic infarction of wide medial parts of the midbrain, mainly the tegmentum, and the right-sided mediobasal parts of the forebrain. Stimulation immediately resulted in autonomic reactions and behavioural arousal reactions during the periods of stimulation. Longterm effect consisted of a rise in the level of clinical responsiveness for a period of seven weeks. A preexistent severe pneumonia disappeared completely after one week of stimulation and returned after seven weeks. The results are discussed on the basis of the pathoanatomical findings and of the physiological functions of the damaged as well as of the stimulated areas.