Thirty three young patients (23 males and 10 females), between 3-20 years of age, with a clinical suspicion of subacute sclerosing panencephalitis (SSPE) were evaluated over a period of 4 years. A past history of measles was obtained in 42.4% of the cases. One child was immunised against measles. Measles specific antibodies (IgG) were demonstrated in the cerebrospinal fluid (CSF) from 30 (90.9%) of the 33 patients by ELISA. In the remaining three cases the antibodies were detected only in the serum. Serodiagnosis of SSPE by ELISA had a sensitivity of 100%, a specificity of 93.3% and a positive predictive value of 100%.