Influenza-associated acute encephalopathy (IAE), a rare and fatal complication of influenza, is more common in Japan than in Europe or in the U. S.. We have induced intracranial pressure (ICP) monitoring since 2002 in the management of infants with IAE in our center. This report describes a survival case of a one-year and four-months old boy with IAE whose ICP was narrowly controlled. The patient was pyrexial, convulsive and comatous at the time of admission and antibodies to Influenza A virus was positive. ICP monitoring was started just after admission and we aimed to maintain his ICP lower than 20mmHg or cerebral perfusion pressure (CPP) higher than 45mmHg. The ICP was controlled with whole body hypothermia with barbiturate infusion and osmolar diuretics. His brain had been almost normal in CT scan on the day of admission but swelled within three days to lose cistern and sulci in the scan. The ICP increased to over 50mmHg against all our efforts and we infused norepinephrine to maintain CPP. The ICP was normalized and ICP monitoring was withdrawn on the 10th hospital day. CT scans and MRI's in chronic phase demonstrated hemorrhagic shock and encephalopathy syndrome (HSES) patterns according to our classification of IAE images. The patient has recovered well without major neurological deficit despite critical ICP in acute phase. We dare to say from our experience that it is difficult without ICP monitoring to manage an IAE infant in the most favourable condition or to cure it without significant neurological sequelae. In conclusion, 1) ICP monitoring in patients with IAE is just as important as with severe head injuries to check sudden increase of ICP, 2) maintaining CPP might be important as well as maintaining ICP within normal limits to improve the outcome of IAE patients.