To characterize cognitive impairments following multiple subcortical lacunar infarcts (lacunes), we prospectively compared the neuropsychological performance of 11 subjects with multiple lacunes with 11 medical control subjects matched for age and education who had no clinical or computed tomographic evidence of central nervous system disease. Subjects with multiple subcortical lacunes displayed neuropsychological signs of frontal system dysfunction, even though only 27% met the criteria for clinical diagnosis of dementia. They exhibited significant deficits in shifting mental set, response inhibition, and executive function. In addition, they were more often rated apathetic on a behavior-rating scale. We propose a continuum of cognitive impairments in lacunar states, ranging from frontal systems impairment to dementia.