Cognitive impairment has been repeatedly shown to be a delirium risk factor. Much indirect evidence suggests that right-hemisphere dysfunction plays a particularly important role. This retrospective, case-controlled study, from a 148-patient memory loss clinic database, compared neuropsychological measures of hemispheric function in cognitively impaired elderly veterans with and without a history of delirium. Eleven study subjects had a history compatible with DSM-III-R criteria for delirium. Controls selected from the same database had no known history of delirium and were matched for Mini-Mental State Examination scores and Geriatric Depression Scale scores. Compared to the controls, subjects with a history of delirium had significantly lower scores on Object Assembly and Visual Reproduction (p < .05), tests that are predominantly right-hemisphere dependent. There were no significant differences in left-hemisphere measures. It is concluded that right-hemisphere dysfunction may prove to be an important risk factor for delirium.