In 1983, Levin et al. described a devastating disease occurring in early childhood called the hemorrhagic shock and encephalopathy syndrome [1] . HSES is not a common disease. Sofer et al. reported 20 patients diagnosed with HSES in a population of about 400,000 over an 11-year period [5] . Our center at Osaka City General Hospital is one of two tertiary pediatric centers in Osaka prefecture. The area our center services for primary referrals has a population of about 4 million residents. However, we do not in any way hypothesize that the 8 patients in our 6year study were the only cases of HSES in this large region, as compared with the 20 patients in the 11-year Sofer et al. report of a significantly smaller population [5] , as there were most likely other HSES patients who could not be transferred to our center from other hospitals due to the rapid deterioration of their conditions. Most reported cases of HSES occurred in winter [3, 5] ; as in the present study, further supporting this evidence, 50% of our patients were admitted in winter, between December and February.