To see if the treatments of d-amphetamine and chlorpromazine have any influence upon the orienting response and general behavioral activity, 3 groups of male Holtzman rats were prepared, namely d-amphetamine animals (1.0 mg/kg.i.p.), chlorpromazine rats (1.0 mg/kg.i.p.) and the physiological saline control animals. The general behavioral activity was examined by visual scanning using the time-sample method in the adaptation period of orienting response. The occurence of orienting response and its rate of habituation were evaluated by observing cessation of ongoing activity in response to a sound stimulus (1,000 Hz, 70 db & 0.1 sec), or turning of head toward the source of stimulus in 20 trials. Attention shift from sound to light stimulus was also tested in 10 trials. The results obtained were as follows; 1. The general behavioral activity of d-amphetamine group was significantly greater than that of control, however, the chlorpromazine animals showed the tendency to decrease in activity. 2. The d-amphetamine group showed the occurence of orienting response to sound significantly more often than that of placebo controls. However, the chlorpromazine group exhibited significantly fewer orienting response than the placebo group did. 3. The d-amphetamine group displayed no clear out habituation to the orienting response following the repetition of trials, though the placebo and the chlorpromazine groups demonstrated apparent habituation to the response. 4. The three animal groups did not differ significantly from each other with regard to shift of attention from sound to light stimulus. It is inferred that the d-amphetamine tends to increase general activity has a definite facilitative action of orienting response and a inhibitory influence upon the habituation of the latter response. On the contrary, the chlorpromazine tends to decrease general activity, has a inhibitory action of orienting response and facilitatory action of habituation of the response.