Fifty-nine children with Japanese encephalitis admitted in Maharaj Nakhon Chiang Mai Hospital since 1984-1985 were studied. The male to female ratio was 1.18:1. The age range was between 1 to 14 years old with 74% in the age range of 6-14 years. The symptoms included change of consciousness (100%), fever (96%), headache (76%), convulsions (59%) and vomiting (52%). The neurologic signs, namely positive meningeal signs (61%), hyperreflexia (61%), positive Babinski's sign (49%) hemiplegia (42%), papilledema (22%), and other cranial nerve palsies (23%) were seen. Abnormal respiration were found in 23% and 8% of cases had hypertension. Most children (81%) had blood leukocytosis with predominant neutrophils. The average CSF white blood cell count was 200 cells per mm. with lymphocytosis in 76 percent of the patients. The average CSF protein was higher than normal. Almost all cases had normal CSF sugar levels. The JEV antibody response, mostly primary type, Occurred in about 62 percent of cases. All children received symptomatic and supportive treatment, such as antipyretics, anticonvulsants, anticerebral edema agents, adequate respiration and nutrition and physical and occupational therapies. Associated complications were treated according to the individual's need. The mortality rate and neurological sequelae were found in 17% and 57% of cases respectively. Eighteen percent of the patients suffered severe neurological sequelae. The neurological sequelae included memory deficit (46%), mental retardation (42%), hemiplegia (34%), emotional and behavioral disturbance (24%), epilepsy (20%), motor aphasia (16%), cranial nerve palsies (16%), involuntary limb movement (8%) and blindness (2%).