Hantaviruses are zoonotic diseases that affect humans and have a worldwide distribution. The hemorrhagic fever associated with renal syndrome occurs endemically in the Asian and European continents affecting housauds of people every year. Hantavirus cardiopulmonary syndrome, recognized as a clinical entity since 1993, represents the prototype of emerging diseases and is distributed in countries of the American continent, including Brazil. Both diseases are transmitted to man through the inhalation of viral particles, which are shed in feces and urine of wild and domestic rodents. They comprise a group of febrile diseases that can affect many organs, particularly the kidneys in the hemorrhagic fever associated with renal syndrome and the lungs and heart in the hantavirus cardiopulmonary syndrome. The lethality of American hantaviroses reaches 50%. The diagnosis of these diseases is performed using serological tests such as immunoenzymatic assays which detect specific antibodies of the IgG and IgM classes. There is no specific treatment. Therefore, special attention should be directed to restore and maintain fluid balance, timely indication of dialysis for renal failure and administration of vasoactive drugs during periods of hypotension and shock. The administration of corticosteroids and/or ribavirin are under evaluation. The number of cases of hantavirus infection has been increasing in Brazil year after year, and it is important to alert health personnel to the occurrence of these entities throughout the country. Awareness of their presence should improve the quality of medical care.