The members of the Hantavirus genus of the family Bunyaviridae are spherical, enveloped viruses containing tripartite negative-sense RNA as their genome. The three genomic RNA segments, designated L, M, and S, encode an RNA-dependent RNA polymerase, envelope glycoproteins (G1 and G2), and nucleocapsid (N) protein, respectively. Hantavirus infections can cause two serious and often fatal human diseases, hemorrhagic fever with renal syndrome and hantaviral pulmonary syndrome, characterized by lung damage and cardiac dysfunction. Humans are infected with hantaviruses from rodent reservoirs that are persistently infected without signs of disease. HCPS due to the Andes virus infection, has a case fatality percentage of about 25-35% in Argentina and of 37% in Chile. ANDV, lineage ANDV-Sout, is the only hantavirus for which a person-to-person transmission has been described. Several ANDV strains are co-circulating in Argentina, e. g. Bermejo, Lechiguanas, Maciel, Oran and Pergamino, whereas HCPS cases were also reported in Bolivia, Brazil, Paraguay and Uruguay. Only for Chile and Argentina can they be strictly associated with ANDV. In Argentina and Chile, the long-tailed rice rat, Oligoryzomys longicaudatus, and other species of the genus Oligoryzomys represent the reservoir for ANDV. Another unique characteristic of ANDV is the availability of an animal model. ANDV causes lethal disease in the Syrian Hamster that closely models the course of disease progression in humans, including a rapid progression from first symptoms to death, including fluid in the pleural cavity and the histopathology of the lungs and spleen. Lethality of ANDV in hamsters is not true of all HCPS viruses, as challenge with Sin Nombre virus shows no symptoms of disease. The availability of this model allows for the study of various drugs and other treatments that may have an impact on the treatment of all HCPS-causing hantavirus infections.