Gm phenotype or haplotype frequencies are known to be increased in some neurological diseases involving dysregulation(s) of the immune system. Therefore, possible associations between acute measles encephalitis (AME) or subacute sclerosing panencephalitis (SSPE) and alleles of the Gm system were investigated by comparison of children (41 AME subjects and 62 SSPE subjects) with 378 ethnically and geographically matched controls. Although the Gm3;..;11 haplotype displayed a very low frequency among SSPE children, no statistically significant departure in the distribution of Gm phenotypes could be evidenced between AME or SSPE, and controls. A further appraisal of combined Gm and HLA phenotypes may be warranted in both diseases since Gm/HLA interactions have been demonstrated in other immunopathological conditions.