We report the fourth case of cerebral demyelinating disease associated with 5-fluorouracil and levamisole hydrochloride therapy for adenocarcinoma of the colon. The initial manifestations included subacute progressive decline in mental status, ataxia, dysarthria, and diplopia. Magnetic resonance imaging of the head demonstrated multifocal enhanced lesions in the white matter. The patient experienced improvement, without corticosteroid treatment, from 2 weeks to 4 months after cessation of chemotherapy.