We studied 36 patients (24 males, 12 females), all of whom had definite subacute sclerosing panencephalitis with typical periodic complexes in their electroencephalograms and increased titers of measles antibody in serum and cerebrospinal fluid. Their clinical and laboratory findings on admission were reviewed retrospectively. The age at onset of symptoms varied from 4 to 23 years. The average age at onset of disease was 13.1 +/- 4.18 years. The mean of the duration from the infection to the onset of subacute sclerosing panencephalitis was 9 years. Unusual symptoms, especially in the early periods of disease, included hemiparesis (7 patients), headache (3), generalized tonic-clonic seizures (6), absence seizure (1), nausea (3), and vomiting (3). Twenty-six cranial magnetic resonance imaging (MRI) and 12 computed tomography examinations were performed. Nine patients had normal MRI. In the early stages, lesions usually involved parieto-occipital corticosubcortical regions asymmetrically. In time, symmetric periventricular white-matter changes became more prominent. In addition to the common clinical findings in cases of subacute sclerosing panencephalitis reported in the literature, there were some different clinical features of the disease. Eventually, we concluded that there seems to be no correlation between the clinical stages and either the duration from the onset of subacute sclerosing panencephalitis or the MRI findings.