When 7 mice injected with methamphetamine (5 mg/kg, s.c.) were placed together into a box with a limited space maintained at 28-30 degrees C, the grouped mice showed extreme behavioral excitation consisting of 2 typical features: fighting behavior with squeak and hyperactive behavior characterized by running and jumping. The effects of various drugs tested, according to the minimal effective doses (mg/kg, p.o.) which inhibited fighting behavior and hyperactive behavior respectively, were: haloperidol, 0.1 (fighting)--0.25 (hyperactivity); clothiapine, 1 - 1; perphenazine, 1 - 1; thiothixene, 1 - 5; chlorpromazine, 5 - 10; diazepam, 5 - 100; reserpine, 100 - 100; phenoxybenzamine, 200 - 200 (no effect). Major tranquilizers except rauwolfia alkaloids completely inhibited both types of excited behavior at low doses, as compared with the taming effects of the drugs on footshock-induced fighting episodes in pairs of mice. On the other hand, minor tranquilizers suppressed only fighting behavior, showing little effect on hyperactive behavior. None of the antidepressants, adrenergic blocking agents and other drugs showed antagonism to both types of excited behavior. The results indicate that this method may be useful for the evaluation of psychotropic drug effects in grouped mice.