An association of Chandipura (CHP) virus with an explosive outbreak of encephalitis in children from India affecting 349 children with 55% mortality was recently reported. To understand the role of cytokines in the pathogenesis of CHP infection, 14 paediatric encephalitis cases admitted to a tertiary care hospital and 5 age-matched apparently healthy control children were studied. At the time of sampling, post onset of disease was < or =2 d (Group A, n = 4) and >2 d (Group B, n = 10). Concentrations of IL-2, IFN-gamma, TNF-alpha and IL-6 in mitogen stimulated PBMC supernatants of patients and controls were assessed by ELISA. IL-2 levels in Group A and B were significantly higher compared with controls (28.4+/-21.9 vs <7.8, p=0.01, 269.4+/-311.0.vs <7.8, p = 0.01). IFN-gamma levels were significantly elevated in both the groups compared with controls (394.4+/-107.7 vs 13.9+/-20.9, p = 0.01, 339.5+/-244.9 vs 13.9+/-20.9, p = 0.01). TNF-alpha and IL-6 levels were significantly higher in Group B compared with controls (573.1+/-472.5 vs 113.4.+/-148.3, p = 0.01, 486.2+/-145.7 vs 113.8+/-82.4, p = 0.003). Cytokine levels were not significantly different in Groups A and B.