BACKGROUND Dengue is a mosquito borne viral infection in tropical and subtropical regions caused by one of the four serotypes of dengue viruses (DENV1-DENV4). The consequences of DENV infection range from asymptomatic condition Dengue Fever (DF) or severe forms such as Dengue Haemorrhagic Fever (DHF) and Dengue Shock Syndrome (DSS). The host immune responses have been considered as the major factor responsible for dengue pathogenesis. Endothelial activation markers such as expression of adhesion molecules and receptors have been found to serve as biomarkers of severe dengue disease. In this study, the cytokine IL-4 is reviewed for its utility as potential biomarker of severe dengue disease. MATERIALS AND METHODS 120 children of paediatric age group from 1 month till 18 years of age with fever for more than 5 days with either dengue NS1 antigen or dengue IgM positive were included. 30 children who were admitted for noninfectious disease (e.g. surgery) without fever, any systemic illness and preexisting illness (tuberculosis, asthma) in SRMC and RI were taken as controls. Cases were classified as uncomplicated dengue (dengue without warning signs) and complicated dengue (dengue with warning signs and severe dengue). Clinical features and IL-4 (ELISA kit) were analysed and compared among the study population and statistical analysis done for the obtained data. RESULTS Analysis of clinical features among the study groups revealed children with complicated dengue had persistent vomiting (95%), abdominal pain (80%), decreased urine output (50%), bleeding manifestations (83.3%), hepatomegaly (70%), haemoconcentration with concurrent thrombocytopenia (93.3%), altered coagulation profile (28.3%), ICU stay (54.7%), leucocytosis (15%), leucopenia (66.6%) and normal leucocytes (18.4%). Analysis of IL-4 levels revealed children with complicated dengue showed >6 fold elevation in IL-4 levels (p=0.003). Mean IL-4 levels in complicated dengue group was also statistically significant (p=0.013). ROC curve for IL-4 indicated 50% reliability as predictor for dengue severity. CONCLUSION In our study, IL-4 levels were significantly higher in complicated dengue patients in comparison with uncomplicated dengue patients as well as normal control population. Though, this interleukin 4 can be used for assessing the severity of children with dengue, further studies with higher sample size are needed to advocate the routine use of IL-4 as a biomarker of dengue severity.