Serum and cerebrospinal fluid (CSF) from eight patients with subacute sclerosing panencephalitis (SSPE), 21 with multiple sclerosis (MS) and 16 controls were analyzed for IgG subclass pattern of anti-viral and anti-bacterial antibodies. In CSF of SSPE and MS patients IgG1 and IgG4 antibodies to measles and IgG1 to mumps were increased compared to the controls. In addition, the SSPE patients had elevated levels of IgG1 to PPD, teichoic acid, and to dextran in CSF. The group of MS patients had decreased levels of IgG1 antibodies to Staphylococcus aureus alpha-toxin.