Severe-type Kawasaki disease (KD) complicated by serious myocarditis and encephalopathy can be successfully treated without abnormality of the coronary arteries by steroid pulse treatment and intravenous immunoglobulin (IVIg). A 4-year-old Japanese girl was diagnosed with KD due to a 6-day history of fever, rash, flushed lips, conjunctival hyperemia, palmar edema, and cervical lymphadenopathy. The day after initiation of IVIg and aspirin, cardiac gallop rhythm was identified. Cardiac ultrasonography revealed severe left ventricular dysfunction. Disturbance of consciousness, hallucinations, and slurred speech were also observed. Magnetic resonance imaging showed no abnormalities, but electroencephalography revealed high-voltage slow waves. Despite this serious disease, cardiac function and neurological abnormalities showed complete recovery without dilatation of the coronary arteries by steroid pulse treatment and additional IVIg. Follow-up at 15 months revealed no abnormality of the coronary arteries. In conclusion, we suggest that early combined treatment with steroid and IVIg is effective for serious KD complicated by myocarditis and encephalopathy. J. Med. Invest. 63: 140-143, February, 2016