| - Introduction: Exudative tonsillitis is a common clinical picture during childhood. The majority of these cases are caused by viruses (Epstein-Barr virus [EBV], cytomegalovirus [CMV], influenza virus, parainfluenza virus, and adenovirus), and only some infections are caused by bacteria, mainly group A streptococci (GAS). On the basis of international guidelines, routine use of early antibiotic treatment is not recommended in these cases, because it seems not to prevent GAS-associated complications. Aim: Our aim was to determine those laboratory results which are useful to distinguish between bacterial and viral infections in children with exudative tonsillitis to reduce antibiotic overuse. Method: In our study, we evaluated 135 clinical data from 133 children with exudative tonsillitis. Patients were grouped according to the following criteria: the first group contained patients with acute CMV or EBV infections, while in the second group, CMV or EBV infections were not confirmed using serology. Results: On the basis of our results, EBV or CMV infections (66/135, 48.8%) were serologically confirmed in the majority of cases with exudative tonsillitis between 2016 and 2017, while the causative role of GAS was minimal in this patient group (3/65, 4.61%). In spite of this finding, the majority of patients (92%) were treated with antibiotics. Conclusion: Our retrospective findings confirmed that it is not possible to determine the causative agent of this clinical picture on the basis of symptoms, and physical findings, moreover laboratory results, such as high white blood cell count could not confirm bacterial infection. At the same time, elevated transaminase levels may refer to viral origin of infection, especially EBV or CMV with high predictive value; the use of extended laboratory tests may reduce the unnecessary antibiotic consumption. Orv Hetil. 2020; 161(2): 50-55.