Group A streptococcus (GAS) rarely causes meningoencephalitis in children without risk factors. A previously healthy 8 year-old child presented with lethargy, high fever, and vomiting. The clinical course was unusual including intractable seizures, disseminated intravascular coagulation (DIC), and left hemiparesis in spite of the appropriate and timely administration of antibiotics and corticosteroids. The microbiologic studies revealed that the pathogen was susceptible to penicillin and GAS M18 strains. This case showed the importance of the GAS vaccine in addition to appropriate antibiotics.