Clinical, radiological, and histological examinations were performed on eight patients with autosomal-dominant dentato-rubro-pallido-luysian atrophy (DRPLA) including an autopsy case, to investigate the abnormal findings of the cerebral white matter in DRPLA. Three of the eight patients were found to have diffuse low density on CT or diffuse high-signal areas on T2-MRI in the white matter of the brain. There were no correlations between abnormal findings in the white matter and the following factors; age of onset, duration of the disease, clinical manifestations, disease severity, Hachinski score, or EEG abnormality. Single-photon emission tomography failed to reveal any relative decrease in cerebral blood flow in the white matter, even in the three patients with abnormal findings in the white matter. MRI perfusion studies did not suggest any decrease in cerebral blood volume in any of the patients examined, but in the DRPLA patients the latency, i.e., the interval from the time of injection to the time of the minimum signal intensity, was significantly prolonged in comparison with the results in normal controls. On histopathological investigation, there was diffuse decreased staining in the centrum semiovale and deep white matter of the temporal lobes bilaterally, but no gliosis, or arteriolar thickening or hyalinization were detected. These findings confirmed that the lesions in the white matter in DRPLA are not attributable to cerebral ischemia. The abnormal findings are presumably the result of the degeneration which occurs in DRPLA itself.(ABSTRACT TRUNCATED AT 250 WORDS)