We performed a morphometric analysis of cresyl violet-stained sections from the dorsolateral prefrontal cortex of 81 patients with Huntington9s disease (HD) (grades 2, 3, and 4) and 23 age-matched normal controls. We counted large pyramidal neurons, small neurons, astrocytes, oligodendroglia, and microglia under the guidance of a specifically predefined set of morphologic criteria for each cell type and recorded the thickness of each cortical layer. Our results demonstrate a selective and progressive loss of a subset of the large pyramidal neurons in cortical layers III, V, and VI of HD patients, and a decrease in the thickness of the respective cortical laminae. A genetically determined, cell-autonomous degeneration of cortical neurons could constitute the primary pathologic process. However, the loss of only a fraction of pyramidal cells suggests a parallel, or an alternative, possibility of a retrograde degeneration of cortical neurons that project solely, or principally, to the site of primary degeneration in caudate nuclei.