summary A 45-year-old man was admitted to a psychiatric hospital with confusion and disorientation; he was suspected of having Korsakoff syndrome. He was known to have a history of alcohol abuse, complicated by epileptic fits, and to have had a recent ischaemic cerebrovascular attack. Unexpectedly, screening for syphilis turned out to be positive. Examination of the cerebrospinal fluid led to the diagnosis of neurosyphilis. Most neurological and psychiatric symptoms disappeared after treatment with antibiotics.