Many investigators believe that the autonomic nervous system may be involved in minimal brain dysfunction in children. The objectives of our studies are to investigate differences in autonomic functioning between MBD and normal children by means of peripheral indicators such as skin conductance, heart rate and pupillary activity, to predict which MBD children will respond favorably to stimulant drugs, and to assess the effects of the drugs on both autonomic activity and on task performance which depends on attention such as reaction time.