We report a 61-year-old alcoholic man who presented with subacute physical deterioration and severe dysarthria. MRI, suggestive of corpus callosum demyelination with associated white matter involvement in both cerebral hemispheres, indicated the diagnosis of Marchiafava-Bignami disease. During his stay in hospital the patient showed remarkable improvement, and was discharged 22 days after admission. On MRI 2 months later, the extracallosal lesions had disappeared. This case raises questions about some previous ideas on this disease, such as the prognosis of its acute forms and the significance of the extracallosal lesions seen on neuroimaging.