A formerly healthy 48-year-old man was accidentally exposed for approximately 20 minutes to a high concentration of carbon disulphide (minimum concentration, 400 parts/10 6 ; maximum, 470 000 parts/10 6 ), and was unconscious for approximately 10 minutes. Serious persistent cerebral deterioration developed. Computerized tomography scanning showed cerebral atrophy, neuro-psychological examination established dementia, and measurement of cerebral flow showed reduced cortical flow in the right hemisphere. Possible mechanisms for the cerebral damage are discussed, and persons who are at risk from such accidental poisoning are listed.