Maternal treatment with cocaine or the D1-dopamine receptor agonist, SKF 38393, induces expression of the immediate-early gene, c-fos, in fetal rodent brain. Our previous studies have focused on the suprachiasmatic nucleus late in gestation. In the present report, we examined the anatomical distribution of functional D1-dopamine receptors throughout fetal rat brain. Functional D1 receptors were defined using three complementary methods: in situ hybridization to detect D1 receptor mRNA, autoradiographic detection of 125I-SCH 23982 binding, and in situ hybridization to detect c-fos gene expression induced by maternal treatment with SKF 38393. D1-dopamine receptor binding, receptor mRNA, and SKF 38393-induced c-fos gene expression are widespread in fetal brain by late gestation. These data indicate that the fetal brain is sensitive to dopamine receptor activation, and suggest that gestational exposure to drugs of abuse acting via dopaminergic mechanisms may influence fetal brain function.