Magnetic resonance imaging and a comprehensive cognitive evaluation were carried out in a series of 29 patients with mild to moderate Huntington's disease (HD). A factor analysis of the neuropsychological test scores provided three factors: a memory/speed-of-processing factor, a "frontal" factor, and a response inhibition factor. The memory/speed factor correlated significantly with measures of caudate atrophy, frontal atrophy, and atrophy of the left (but not the right) sylvian cistern. There were no significant correlations between the "frontal" or response inhibition factors and measures of cortical or subcortical brain atrophy. Our findings confirm that subcortical atrophy is significantly correlated with specific cognitive deficits in HD, and demonstrate that cortical atrophy also has important association with the cognitive deficits of patients with HD.