The effects of repeated electroconvulsive shock (ECS) on binding parameters of D1 and D2 type dopamine (DA) receptors were investigated in different brain regions of male rats using quantitative autoradiography. D1 binding was studied with [3H]SCH 23390 as the ligand and D2 binding with [3H]spiroperidol. The distribution patterns of both D1 and D2 receptor sites were in good agreement with previously published reports. Repeated ECS induced upregulation of D1 receptors in the olfactory tubercle, the endopiriform nucleus and the substantia nigra without appreciably affecting D1 binding sites in the striatum, n. accumbens or in other brain regions containing D1 binding sites. Upregulation of D2 binding sites, after ECS, was seen in the accumbens, the olfactory tubercle, the amygdaloid nuclei, the claustrum and the endopiriform nucleus, but not in the caudate-putamen or in other brain regions containing D2 binding sites. The present finding that repeated ECS can selectively upregulate DA receptor binding sites in discrete brain areas, including limbic structures, renders important support to a large number of previous studies that demonstrated effects of repeated ECS on DA receptor function in behavioral models.