Objective To study the clinical characteristics of Japanese encephalitis (JE) in 34 adult patients and to improve the level of diagnosis of this disease.Methods The clinical manifestations,laboratory results and radiological features of 34 adult patients with JE in our hospital from July 2017 to September 2017 were summarized and the progonsis was observed.The modified Rankin Scale (mRS) was used to evaluate the progonsis.Results Eighteen patients were males and 16 patients were females with the average age of (45.39 ± 16.34) years in 34 patients who were diagnosed as JE.The major clinical features of JE patients included fever (34,100％) with the average temperature of (39.4 ± 1.1) ℃ on admission,headache (26,76％),seizures (7,21％),decreased consciousness (25,74％) on day 2.6 ± 1.4 after the onset,respiratory failure (9,26％) on day 3.8 ± 1.6 after the onset.The major features of laboratory results included white blood cells increase (15,44％),blood hematocrit decrease (25,74％),eosinophil absolute value decrease (29,85％),cerebrospinal fluid pressure increase (12,35％),cerebrospinal fluid protein increase (27,79％),cerebrospinal fluid white blood cells increase (30,88％).Brain MRI scan of abnormal signal was found abnormal in up to 54％patients (14/26),involving the thalamus,basal ganglia,mesencephalon,temporal lobe,hippocampus and occipital lobe,especially in the area of bilateral thalamus and mesencephalon.The follow-up showed three cases were dead;mRS score was 0 in twenty-one cases,1 or 2 in five cases,3 or 4 in three cases,5 in two cases five-six months after onset;the sequelaes were cognitive impairment in nine patients and movement disorder in five patients.Conclusions The clinical symptoms of JE in adults are severe.The main clinical manifestations of JE are hyperthermia,disturbance of consciousness,seizures and respiratory failure,with characteristic imaging findings on brain MRI.JE is a disease with high mortality and severe long-term sequelae.