The ability to exhibit facial expressions was studied in four patients with severe dementia of the Alzheimer type (SDAT), by means of the Facial Action Coding System (FACS) and physiological responses (heart rate, respiration, skin temperature) under pleasant and unpleasant stimulus conditions. Complex facial expressions that could be interpreted as expressions of emotions were not seen. An increase in the number of facial movements and changes in the physiological responses were seen most markedly under the unpleasant stimulus condition. The patients' reactions during the assumed pleasant stimulus conditions indicated comfort. Different reactions were obtained among the patients. The importance of developing further methods to identify and interpret facial movements in nurse-patient relationships is emphasized.