Hantaviruses are assigned to categories A and C on the National Institute of Allergy and Infectious Diseases (NIAID) Priority Pathogens list and to category C on the Centers for Disease Control and Prevention (CDC) Emergency Preparedness and Response list of boterrorism agents/diseases. These rodent-borne viruses are members of the family Bunyaviridae and are transmitted to humans in aerosols of rodent excreta. There are more than 20 recognized hantaviruses, some of which are associated with one of two serious human diseases: hemorrhagic fever with renal syndrome (HFRS) or hantavirus pulmonary syndrome (HPS). Because of the global distribution of hantaviruses, the historical association of HFRS-causing viruses with military operations and the recent emergence of the HPS-causing viruses, efforts are continuing to develop safe and effective hantavirus vaccines. This review addresses the significance of hantaviruses as they relate to biodefense and provides information about conventional and molecular vaccines for HFRS that have advanced to clinical studies.