Book excerpt: This monograph describes the progress in neuropathological HD research made during the last century, the neuropathological hallmarks of HD and their pathogenic relevance. Starting with the initial descriptions of the progressive degeneration of the striatum as one of the key events in HD, the worldwide practiced Vonsattel HD grading system of striatal neurodegeneration will be outlined. Correlating neuropathological data with results on the functional neuroanatomy of the human brain, subsequent chapters will highlight recent HD findings: the neuronal loss in the cerebral neo-and allocortex, the neurodegeneration of select thalamic nuclei, the affection of the cerebellar cortex and nuclei, the involvement of select brainstem nuclei, as well as the pathophysiological relevance of these pathologies for the clinical picture of HD. Finally, the potential pathophysiological role of neuronal huntingtin aggregations and the most important and enduring challenges of neuropathological HD research are discussed.