Fil: Gonzalez Della Valle, Marcelo. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Virología. Laboratorio de Hantavirus; Argentina.Fil: Edelstein, Alexis. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Virología. Laboratorio de Hantavirus; Argentina.Fil: Miguel, Sergio. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Virología. Laboratorio de Hantavirus; Argentina.Fil: Martínez, Valeria Paula. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Virología. Laboratorio de Hantavirus; Argentina.Fil: Cortez, J. Hospital San Vicente de Paul; Argentina.Fil: Cacace, María Luisa. Hospital San Vicente de Paul; Argentina.Fil: Jurgelenas, G. Hospital del Milagro. Laboratorio de Hantavirus; Argentina.Fil: Sosa-Estani, Sergio. ANLIS Dr.C.G.Malbrán. Centro Nacional de Diagnóstico e Investigación en Endemo-Epidemias; Argentina.Fil: Padula, Paula. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Virología. Laboratorio de Hantavirus; Argentina.Hantaviruspulmonary syndrome (HPS) hasbeen documented in the Salta and Jujuy provincesof northern Argentina since 1991 and 1997, respectively, accounting for almost 50% of the casesof HPS reported in thiscountry. Andes(AND) virus, specifically the AND virusNort lineage, wasprevious ly associated with human disease in this region. Genetic analysis of viral medium RNA segments obtained from 18 HPS cases showed the existence of three AND virus Nort sublineages co-circulating in these two provinces. They showed a nucleotide sequence diversity of up to 11.1% between the sublineages. The putative site of infection of one of these cases (Sal3/97) was determined. A 100% nucleotide sequence identity was observed between the viral sequence found in patient Sal3/97 and in two virus-positive Oligoryzomys chacoensis captured in the same place where the case lived and worked. These results indicated the putative site of infection and identified thisrodent speciesasthe source of infection.