An autopsy case of primary cerebral malignant lymphoma with choreoathetosis as initial and main symptom was reported. A 57-year-old woman showed choreoathetosis in right upper and lower extremities, and mental aberration. Cranial CT scan showed high density areas in bilateral frontal lobes, right caudate nucleus and putamen, right vermis of cerebellum, left corpus callosum, all of which revealed increased high density by enhancement. The diagnosis of malignant lymphoma was confirmed by the findings of CT scan-guided stereotaxic biopsy. Although the consciousness became gradually drowsy, neurological signs and symptoms and cranial CT scan's findings were improved by radiation therapy. Subsequently, she developed paresis of left upper and bilateral lower extremities and died of sepsis and disseminated intravascular coagulation 8 months after the onset. Neuropathological examination revealed macroscopically atrophy and brawnish discoloration in bilateral caudate nuclei and right globus pallidus. Microscopically, there were invasions of tumor cells in the subependymal perivascular space of ventricles and subarachnoidal spaces of cerebellum and brainstem. The bilateral heads of caudate nuclei revealed severe atrophy, neuronal loss and astrocytic proliferation induced by tumor cell invasion into the head of caudate nuclei, of which body and tail were well preserved. The globus pallidus and putamen did not show any abnormalities on left side, but the right globus pallidus was atrophic, and middle part of putamen and globus pallidus showed tissue rarefaction, loss of myelin, and astrocytic proliferation. However, neuronal cells were relatively preserved. In the spinal cord, the tumor cells invaded to the subarachnoidal and perivascular spaces and necrosis of spinal parenchyma were noted from lower cervical to upper thoracic cord.(ABSTRACT TRUNCATED AT 250 WORDS)