Cerebral lymphoma is infrequent in immunocompetent patients. This tumour usually appears on CT and MRI as a single lesion or as multiple lesions with mass eVect and homogeneous enhancement after contrast administration. A patient is described with a cerebral lymphoma, confirmed by histopathological examination, who presented as a progressive leukoencephalopathy. (J Neurol Neurosurg Psychiatry 2001;71:243-246)