We have examined the immunoreactivities of a glutamate (Glu) transporter, GLT-1, in rat brains treated with a single or repeated intermittent administration of methamphetamine (MAP). In the stratum of behaviorally sensitized rate induced by repeated intermittent MAP treatment, GLT-1 immunoreactivities were increased by 51%. There was no difference in the GLT-1 immunoreactivities in all regions examined between rate treated with a single administration of MAP and the control rats. These results suggest that hyperglutamatergic activity in the striatum is involved in the induction of behavioral sensitization caused by MAP.