Magnetic resonance imaging was conducted on six children and adolescents with fetal alcohol syndrome and seven matched normal controls. Detailed volumetric analyses demonstrated significant reductions in the cerebral vault, basal ganglia, and diencephalon in the children with fetal alcohol syndrome, compared with control children. In addition, the volume of the cerebellar vault was smaller than controls in 4 of the 6 children with fetal alcohol syndrome, although the group difference did not reach significance. When the basal ganglia were divided into the caudate and lenticular nuclei, both of these regions were significantly reduced in the children with fetal alcohol syndrome. Finally, when the overall reduction in brain size was controlled, the proportional volume of the basal ganglia and, more specifically, the caudate nucleus was reduced in the children with fetal alcohol syndrome. These results may relate to behavioral findings in both humans and animals exposed to alcohol prenatally.