Dengue Hemorrhagic Fever (DHF) and Dengue Shock Syndrome (DSS) are the severe and/or fatal clinical manifestations of dengue fever. Epidemics of DHF/DSS occur mainly in the southeast Asian countries where children are seriously affected and high case-fatality ratio is annually reported. Recently significant epidemics of DHF/DSS have been reported in Cuba, Venezuela and Brazil, which means that reinforcements of the epidemiological surveillance in the countries of the American region that show high virus transmission, are urgently needed. The main purpose of the present article is to review relevant information regarding the clinical manifestations, pathology, diagnostic procedures, treatment of cases, pathophysiologic mechanisms and some data related with specific DHF/DSS epidemics.