BACKGROUND: Acute Febrile illness remains the leading cause of hospitalisation among adults and children in urban and rural regions of Southeast Asia(1). The Infectious diseases like dengue,enteric fever, leptospirosis, and scrub typhus are the common causes of Acute Febrile Illness. symptoms of such tropical diseases overlaps during the initial period of infection.CRP, an acute phase reactant, is gaining focus recently in delineating bacterial from viral infections. OBJECTIVE:To emphasize the usefulness of CRP in delineating bacterial from viral infections,in cases of acute febrile illness. METHODOLOGY:An observational study is conducted in a diagnostic lab of an NGO,Helping Hand Foundation,in Hyderabad.A total of 76 Patients were included in the study.The samples were received at the lab for analysing fever prole,during a period of 2 months i.e of September2021 to October2021. RESULTS:Out of 76 patients included in the study,21(28%) patients were diagnosed as having typhoid.15 (20%) were diagnosed with positive dengue serology and remaining 40 (52%) patients were included as having Acute Undifferentiated fever(AUF) with undetermined etiology and needs further evaluation. The p value for CRP levels,was calculated between the groups with signicant widal titres and positive dengue serology,which came as (p=0.0024)(C.I 95%),which is considered statistically signicant by conventional criteria. CONCLUSION:CRP levels are signicantly elevated in enteric fever cases when compared to the patients with positive dengue serology.Thus CRP can be a useful tool along with other blood investigations in differentiating bacterial and viral causes of Acute febrile illness.