Eticlopride is a potent and selective D2 receptor antagonist that has been studied in rats with extensive dopamine denervation induced by 6-hydroxydopamine. Administering Eticlopride daily for 21 days increases D2 receptor density in intact brain regions; however, it does not further elevate the already increased density in denervated areas. Despite changes in receptor density, functional sensitivity remains evident, as demonstrated by the contralateral rotations induced by the D2 agonist quinpirole during the washout period. This study suggests that chronic D2 receptor blockade and dopamine denervation may share a common mechanism in upregulating D2 receptor density, contrary to previous reports of additive effects with denervation and antagonist treatment.