In 1978, hantaviruses were first described as the etiological agent of hemorrhagic fever with renal syndrome (HFRS) in Korea. Since then, numerous related, enveloped, negative-stranded RNA viruses have been identified, forming the genus Hantavirus within the family Bunyaviridae. These pathogens are distributed worldwide and thus can be classified, on the basis of phylogenetic origins, into Old World viruses or New World viruses (ie North, Central, and South America). Similarly, these viruses cause two major types of syndromes, corresponding respectively to their phylogenies: the original HFRS or the more recently described hantavirus pulmonary syndrome (HPS). As the hantavirus pulmonary syndrome is the primary hantaviral disease in North America, it will thus be the focus of this review.