In 25 patients with subacute sclerosing panencephalitis in various phases of the disease CT and NMR imaging of the brain were done at the same times and the findings were related to clinical symptomatology. NMR imaging, in contrast to CT imaging, demonstrated even very small brain changes in the initial stage. The inflammatory-demyelinizing process begins in SSPE as a rule in the white matter of the occipital lobes, and only later in appears in the vicinity of the anterior horns of the lateral ventricles. Spreading of subcortical changes in the occipital lobes and their later penetration into the parietal lobes causes the development of ideatory apraxia frequent in these cases, and involvement of the cortex of the occipital lobes leads to visual agnosia. The paresis of extremities in later stages not always are correlated with greater intensity of changes in the contralateral cerebral with greater intensity of changes in the contralateral cerebral hemisphere. Hydrocephalus developing after longer duration of the disease is an expression of postinflammatory brain atrophy and not of disturbances in cerebrospinal fluid absorption.