A 24-year-old man with livedo racemosa and psychiatric disturbances, manifesting as low intelligence (IQ 80) and delusions, had anti-cardiolipin antibody and showed shortening of the fingers and toes. A skin biopsy of the livedo lesion revealed endoarteritis obliterans, being compatible with Sneddon's syndrome. MRI of the brain demonstrated multiple infarction and moderate cortical atrophy. A single photon emission tomography of the brain showed a marked reduction of the blood flow in the front-temporal lobe. These findings might relate to the psychiatric disturbance. After intravenous administration of cyclophosphamide and the start of oral prednisolone, the anti-cardiolipin antibody level decreased and his physical condition improved. However, a low dose of haloperidol is still necessary to maintain his mental condition.