We traced 85 Japanese encephalitis (JE) patients, 6-27 years after hospitalizations. The first control group was made up of 73 non-JE encephalitis patients 6-27 years previously, whereas the second control group was made up 78 neighborhood residents, matched to the 78 surviving JE cases by age, sex, and residence. All subjects were examined with neurologic examinations, intelligence quotient (IQ) measurement, Mini-Mental State Examinations (MMSE), and activities of daily living (ADL) assessments. At follow-up, 22% of JE patients had objective neurologic deficits compared with 3% of non-JE encephalitis patients. Moreover, 28% of JE patients had subnormal IQs, as opposed to 2% non-JE encephalitis patients. Abnormal ADL scores were only noted in 15% JE patients. All neighborhood controls had normal examination results, and one non-JE encephalitis case showed mildly reduced IQ. The study showed that significant neurologic and overall functional disability were evident in a high proportion of JE survivors many years after their index hospitalizations.