Dengue viral infections are a major cause of morbidity and mortality in tropical/subtropical countries. Although, still a great challenge but early detection of dengue hemorrhagic fever may help to identify individuals that would benefit from intensive therapy. Cytokines are believed to be involved in the pathogenesis of dengue. The potential predictive role of plasma interleukin-10(IL-10) as a marker of disease progression in DHF patients was evaluated. The plasma IL-10 levels between 4 to 7 days of onset of disease and 24 hours after the first sample were determined and the plasma IL-10 levels with the outcome in 50 adult, DHF patients of either sex were related. Plasma IL-10 levels were found to be raised in DHF patients, and were positively related with fatal outcome. In recovered DHF patients, plasma IL-10 levels tended to decrease, but in case of DHF patients in shock, plasma IL-10 was found to be higher after 24 hours. It was concluded that elevated plasma IL-10 is a potential predictor of disease severity and clinical outcome in DHF patients.