Postnatal development of dopamine D1-like (D1/D5) receptors in rat caudate-putamen (CPu), nucleus accumbens (NAc), hippocampus, frontal and entorhinal cerebral cortex was assessed between postnatal days (PD) 7-60 by in vitro receptor autoradiography. Density of [3H]SCH-23390 binding to D1-like receptors increased from PD-7 to a peak at PD-28 in CPu (11-fold) and NAc (23-fold), then declined by 20-40% in both regions over PD-35-60, to adult levels. In hippocampus, frontal and entorhinal cortex, D1-like receptors increased by lesser amounts (3- to 4-fold) from PD-7 to stable, maximal adult levels at PD-60. Evidently, excess D1-like receptors were eliminated during maturation of CPu and NAc, but not in the other forebrain regions. Postnatal D1-like receptor development in rat forebrain paralleled that of D2- and D4-like receptors in the same regions.