Background: The most challenging problem associated with patient management in Dengue infection is early diagnosis. Secondary infection with dengue virus is the most accepted risk factor for the development of dengue haemorrhagic fever. Serologic diagnosis of dengue virus infection using ELISA of both IgM and IgG distinguishes primary and secondary infections. Aim: to determine the seroprevalence of dengue viral infection using IgM antibody capture ELISA for the early diagnosis in Bihar region. Material and methods: This was a prospective observational study conducted in the Department of Microbiology Jawaharlal Nehru medical college and Hospital, Bhagalpur, Bihar, India for 1 year. A total of 570 serum samples from suspected dengue cases attending OPD or admitted in the hospital were tested for the confirmation of Dengue. We have received blood samples in our microbiology laboratory, the blood samples were allowed to clot at room temperature and then we centrifuged the samples and serum samples were separated. From the serum samples we have done NS1 Ag and IgM Ab testing by ELISA. Results: Out Of 570, 110 samples were positive for dengue. Seroprevalence of Dengue was 19.30%. Out of 110 dengue patients 72 (65.46 %) were male patients and 38 (27.14 %) were female patients. Out of 110 dengue patients, 80(72.73%) patients were from urban area and 30(27.27%) from rural area. In our study dengue infection was observed more (30.90%) in the age group 20 to 30 years followed by 10 to 20 years (23.64%) and 30 to 40 years (21.82%). All dengue positive patients in our study had fever of 2 to 7 days. The most common presenting symptoms of dengue were fever with body ache (46.36%), headache (37.27%), nausea (33.64%) and vomiting (22.73%). Out of 110 dengue cases fever with rash was observed in 8 cases (7.27%). Conclusion: The present results revealed that the study region is epidemic for dengue viral infection and there is an urgent need for the constant monitoring to control further spreading of the infection in the community, hence serological test have important role in the early diagnosis.