Recent observations that Rattus rodents in Asia harbor Hantaan (HTN)-like viruses associated with hemorrhagic fever with renal syndrome led us to investigate the possibility that similar viruses might be present in the United States. Wharf rats were captured at major port cities, their sera were examined for HTN antibody by immunofluorescent antibody (IFA) assay and tissues from selected antibody-positive rats were examined for HTN antigen. Rats positive for both antibody and antigen to HTN virus were found in Philadelphia, PA and Houston, TX. Infected rats were found clustered in discrete foci where a significant proportion was antibody and antigen positive. Viruses isolated from lung tissues of Rattus norvegicus captured at Philadelphia and Houston were grown in cell culture and shown to be closely related to each other and to the 76–118 strain of HTN virus by IFA, but clearly distinct from HTN by plaque reduction neutralization tests. The isolates appear to be variants of the same new virus, for which the name Girard Point virus is proposed.