Background: Fever of unknown origin (FUO) is an important cause of morbidity and mortality in children, especially in tropical countries with varied aetiology and clinical presentation. Aim of this study is to determine the aetiology and outcome of FUO in Indian children. Study design is Prospective, observational study. Methods: We enrolled 75 children aged 1 to 12 years who were admitted with fever >8 days to the pediatric department of DMCH, Laheriasarai, Bihar from November 2019 to June 2020. Initial evaluation included complete blood count, peripheral smear, urine analysis, chest radiography, blood culture and tuberculin test. Results: In 72 children (96%), a definitive diagnosis could be established, whereas 3 children (4%) remained undiagnosed. Most common aetiology of FUO was infectious disease (90.6%) followed by malignancy (4%) and collagen vascular disease (1.3%). Among the infections group, scrub typhus was found to be the commonest aetiology (52%). Conclusions: Infections were the most common etiological factor for FUO in children aged 1–12 years of our region.