Thalamic degeneration was present in 5 autopsied cases of X-chromosome–linked copper malabsorption (X-cLCM), Menkes' kinky hair disease. Among the thalamic nuclei, those in the formatio paraventricularis, intralamellaris, and extralamellaris were spared. The nuclei projecting to the granular cortices had severe neuronal depopulation. The thalamic nuclei that send axons to the agranular cortices were less often and less severely involved. The thalamic afferent system was intact except for degeneration of the red nucleus. Cerebral cortical lesions varied from case to case and usually were less marked than thalamic neuronal changes.