Neuropsychiatric sequelae are a common feature of acute carbon-monoxide (CO) poisoning-particularly when the patient has experienced an episode of CO-induced unconsciousness. In this case report, we present neuropsychological test data demonstrating the presence of mild cognitive impairments following a chronic (3-year) history of low-level CO exposure that never produced loss of consciousness. Deficits were limited to concentration and memory; performance on measures of general intelligence, visuospatial functioning, and speed and dexterity were well within the normal range.