Acute febrile illness (AFI) is defined as a patient with fever of 38 • C or higher at presentation or history of fever that persisted for 2-14 days with no localizing source. Fever is the main clinical symptom of various tropical infectious diseases. Materials and Methods: Retrospective observational examination was directed after endorsement from the Institutional Ethics Committee in Paediatric division, Apollo General Hospital, AIMSR, Jubilee hills from January 2016 till December 2019. Inclusion criteria: All the patients who were conceded in the ward or emergency unit complications of intense febrile infections, patients a half year to 15 years old were taken for the investigation. Exclusion criteria: Patients with associated infections when the complications cannot be attributed to febrile illness or patients with haematological malignancies, autoimmune disorders, and those on immunosuppressant were excluded from the study. Results : In present investigation, an aggregate of 290 patients with intense identical fever were assessed out of these 157 (63%) were male and 133 (36.6%) were female. In this investigation typhoid fever was the most well-known reason for undifferentiated fever (33.7%) trailed by malaria (25.5%), dengue fever (19.6%), urinary tract disease (8.2%), Acute gastroenteritis (5.5%), Pneumonia (3.1%), Bronchiolitis (2.4%), Hepatitis (1.0%) and Pharyngotonsillitis (0.6%%). Conclusions : It is important to know the aetiology and clinical pattern of acute undifferentiated fever for their proper management and it will help to prevent morbidity and mortality.