The afferent nerve terminal in the human globus pallidus, which receives the projection nerve fibers from both the striatum and the subthalamic nucleus, were clearly visualized immunohistochemically using antibodies to calcineurin, synaptophysin, Met-enkephalin (MEnk) and substance P (SP). In normal control case, MEnk and SP-like immunoreactivities were densely localized in the external and internal pallidal segments, respectively, whereas calcineurin and synaptophysin were distributed throughout the globus pallidus. Calcineurin, synaptophysin, MEnk and SP-like immunoreactive peroxidase products decorated most of the long radiating dendrites and the cell bodies of the pallidal neurons. In the cases with Huntington's disease (HD) and striatonigral degeneration (SND), marked loss of calcineurin, MEnk and SP-like immunoreactivities was seen in the globus pallidus corresponding to areas of striatal neurodegeneration, whereas synaptophysin immunoreactivity remained in areas which revealed almost complete loss of calcineurin, MEnk and SP-like immunoreactivities. Calcineurin, MEnk and SP, which show difference in their localization patterns, may provide reliable markers for the striatal efferent nerve terminals, and synaptophysin for the entire pallidal afferent nerve terminals. This report demonstrates the distribution patterns of these neurochemical molecules in the globus pallidus with HD and SND.