A thorough revision on hemorragic dengue fever is presented. Dengue, an acute mosquito-borne infectious disease has occurred in epidemic form in Cuba 1981, causing death of 158 persons. The disease in its classical form was first reported in 1823 but in 1953 a new presentation characterized by hemorrhagic manifestations, shock and a high mortality was observed in Manila, Phillipines. This form was called Hemorrhagic Dengue Fever and Dengue Shock Syndrome (HDF/DSS). Its pathogenesis can be explained by two different theories: it could be a primary infection or a hipersensibility reaction depending on a previous infection.