A simple and rapid technique of destroying the dopaminergic nerve terminals in the corpus striatum of the mouse has been developed. After unilateral injections of 6-hydroxydopamine into the striatum, mice exhibited marked ipsilateral reductions in forebrain dopamine concentrations and turned preferentially toward the side of the lesion (ipsilateral turning). Several psychomotor stimulants ((+)- and (−)-amphetamine, amantadine, caffeine, amfonelic acid, pipradrol and methylphenidate) increased the ipsilateral turning; morphine and clonidine were without effect. Apomorphine and l-DOPA, in doses too low to produce motor stimulation, caused contralateral turning. Turning evoked by (+)-amphetamine, but not by apomorphine, was blocked by α-methyltyrosine. Turning behavior as performed in these experiments is a simple but very sensitive index of central dopaminergic receptor stimulation.