Dengue viruses belong to the family Flaviviridae and have 4 subtypes ( 1-4). Dengue virus is transmitted by the mosquito Aedesaegypti and Aedesalbopictus, widely distributed in Tropical and Subtropical areas of the world. Dengue is considered to be the most important arthropod borne viral disease due to the human morbidity and mortality it causes. The disease may be subclinical, self limiting, febrile or may progress to a severe form of Dengue hemorrhagic fever or Dengue shock syndrome. NS1 antigen is present in high concentrations in the sera of Dengue infected patients during early clinical phase of the disease. It is detected from the 1st to 9th day after the onset of fever in cases of both Primary & Secondary Dengue.