Acute Encephalitis Syndrome is defined as the acute onset of fever and change in mental status (including symptoms such as confusion, disorientation, coma or inability to talk, and/or new onset of seizures) ^[1]. Japanese Encephalitis is a part of broader spectrum of disease known as Acute Encephalitis Syndrome [AES]. Although symptomatic Japanese Encephalitis is rare, the case fatality rate among those with encephalitis can be as high as 30%. Permanent neurologic or psychiatric sequel can occur in 30% - 50% of those with encephalitis ^[2]. It usually affects in the younger group of children between 1-15 years but adult JE cases has also been reported. Aim: The aim of this study was to assess the effect of seasonal pattern of Japanese Encephalitis [JE] cases for the two consecutive years with relation to geographical areas, age, sex, and socio- demographic status of AES suspected patients coming to Patna Medical College & Hospital, Patna. Material and Method: The study was undertaken between January 2015 to December 2016 for the period of two years. The collected CSF and serum samples of patients suspected with AES reaching from various districts of Bihar and nearby places was carried out in the Department of Microbiology, Patna Medical College, Patna. All samples were analysed for JE specific Ig M antibody by IgM Antibody Captured Enzyme Linked Immunosorbant Assay [MAC ELISA]. All the tests performed by the kits supplied by NIV, Pune. Data so obtained were arranged according to year wise, age-group wise, sex-wise, month- wise, and expressed as percentage and numbers as required. Result: A total of 83 JE confirmed cases out of 866 cases between January 2015 to December 2016 were collected. Children of age group 1-15 years were more vulnerable but it was found more or less in every age group. Months of September and October were found to be the peak season for JE infection. No relation was found between male and female patients to JE cases. Conclusion: Rural area was affected more from Japanese Encephalitis than urban areas. It affects low socio economic group of the society especially immune- compromised children to most extent.