AbstractSubcortical projection of the magnocellular medial geniculate body to the lateral segment of the globus pallidus is suggested on the basis of anatomical observations in six Macaca mulatta. In two, extensive decortication failed to produce complete degeneration of the magnocellular division of the nucleus, suggesting the existence of a subcortical projection as well. In four other monkeys, lesions in the globus pallidus produced varying degrees of nerve cell loss with associated gliosis in the magnocellular medial geniculate nucleus. The suggestion is offered that this nucleus is an area of thalamic representation of vestibular function which projects to globus pallidus and vestibular cortex.