Dengue is at present the most important human arbovirosis. It is the main cause of hospitalization and death among children from southeast Asia. Two fifth of the world population live in dengue risk areas. In 1997, over 100 countries reported epidemic and more than 50,000,000 cases and 25,000 deaths were estomated. Nowadays, the Americas is passing through the same situation Asia faced years ago. In 1997, 27 countries reported cases of dengue, and in 14 of them cases of dengue hemorrhagic fever were documented. In all, 387,459 cases of classic dengue and 11,645 of dengue hemorrhagic fever were registered. During the last 2 decades dengue has increased significantly in our region with ups and downs in the annual incidence since 1981. It should be remarked that every 3 or 4 years there is a cyclic decrease and a further increase of the incidence, though it trends to rise. As regards dengue hemorrhagic fever, the situation is not more favorable. The Cuban epidemic that appeared in 1981 was completely untimely in the region. In 1989, 8 years later, the second important dengue hemorrhagic fever epidemic emerged in Venezuela, and from that moment on there has been an increasing tendency of this clinical form of the disease. The factors of the emergence and reemergence are present and rise year after year. The neoliberal policies and the consequent privatization of the health services in most of the countries allow us to watch a gloomy future in relation to the development of dengue and its severe form, the dengue hemorrhagic fever/dengue shock syndrome.