Identification of dengue patients at risk for progressing to severe disease is difficult. Significant plasma leakage is a characteristic of severe dengue infection which can suddenly lead to hypovolemic shock around the time of defervescence. It is hypothesized that the detection of subclinical plasma leakage may identify those at risk for severe dengue. The aim of the study was to determine the predictive diagnostic value of serial ultrasonography for severe dengue. Serial USG, in contrast to existing markers such as hematocrit, may better identify patients at risk for development of severe dengue. Patients with evidence of subclinical plasma leakage and/or an edematous gallbladder wall by ultrasonography merit intensive monitoring for development of complications.Ultrasound is  also useful for early prediction of the severity of dengue fever, thus helps in triage and prevention of those cases which will further progress to dengue haemorrhagic fever or dengue shock syndrome.