Since the identification of the first case of Hantavirus infection in Chile in 1995, a great advance in the knowledge of the disease natural history has occurred. There is evidence to suppose that the infection by Andes virus in suburban areas of Argentina and Chile, whose natural reservoir is Oligoryzomys longicaudatus, has been present but unidentified for a long time. We describe a serologically proven case occurred in 1975. The clinical presentation of the disease slightly differs from that described for Hantavirus Pulmonary Syndrome (HPS), caused by Sin Nombre virus in the USA. There is a wider range of presentation forms including, besides HPS, mild and asymptomatic cases, a greater proportion of renal involvement and pediatric cases. Therefore the epidemiological scenario would be an endemic disease with fluctuations that follow changes in rodent population and their interactions with humans.