Acute undifferentiated febrile illness (AUFI) is a major reason for healthcare consultations in Greater Noida, India. This prospective study was conducted to analyse the epidemiological, laboratory and clinical profile of patients presenting with febrile illnesses from 2017–2021. A total of 1,819 patients, ranging from 1 to 100 years old, both males and females, presenting symptoms of AFI such as loose stools, headache, nausea, breathlessness, abdominal and muscle pain, and vomiting, were enrolled at Yatharth Hospital, Greater Noida, India. Out of total 1819 enrolled patients, 435 (45.5%) were adolescents and children 1 to 20 years old, 732 (80.95%) were adults 21 to 40 years of age, 413 (46.24%) were adults 41 to 60 years of age, 206 (22.87%) were adults 61 to 80 years of age and 33 (3.44%) were adults 81 to 100 years of age. Further, the prevalence of average length of stay (LOS) was stratified as per gender and age groups, the maximum prevalence of length of stay in females was 7286.211 min whereas in male 6646.041 min observed. This research attempts to develop a relationship between AFI and the demographics of sample population of Gautam Budh Nagar in order to understand the causal relation if any so that certain preventive measures could be formulated.