The microvascular architecture of the basal ganglia of human brains was studied on diaphanized specimens after intravascular barium injection and vascular stains. Observation by scanning electron microscope was also performed. The putamen and caudate nucieus showed dense capillary networks. Less dense capillary networks were noted in the capsula interna. The capillary network in the globus pallidus was less dense than that in the striatum but denser than that in the capsula interna. The lenticulostriate arteries ran through the putamen, across the internal capsule and reached the caudate nucleus. Though the arterial branches running within the putamen had many small branches, branching was minimal while crossing the capsula interna and began showing rich ramification again when they reached the caudate nucleus. There were retrograde ramifications in the putamen and caudate nucleus. They appeared to play a significant role in the regulation of blood pressure and are considered to play some role in the occurrence of circulatory disturbances which are prone to involve these structures. The fountain‐like ramifications were seen in the putamen and caudate nucleus, but their function is not clear. In the brains of senile patients, intertwining of the arterial blood vessels was noted in the fountain‐like rami. This structure began to appear in the patients over the age of 50. While the etiology of the intertwining of the arteries remains unknown, its increasing frequency with age supports a hypothesis that this represents a phenomenon correlated with aging or concomitant brain atrophy.