Fil: Salomón, Oscar D.ANLIS Dr.C.G.Malbrán. Centro Nacional de Diagnóstico e Investigación de Endemo-Epidemias; Argentina.Fil: Araki, Alejandra S. Laboratório de Biologia Molecular de Insetos, Instituto Oswaldo Cruz-Fiocruz; Brasil.Fil: Hamilton, James Gc. Centre for Applied Entomology and Parasitology, Keele University, Staffordshire; Reino Unido.Fil: Acardi, Soraya A.Laboratorio de Biología Molecular Aplicada, Universidad Nacional de Misiones, Posadas; Argentina.Fil: Peixoto, Alexandre A. Laboratório de Biologia Molecular de Insetos, Instituto Oswaldo Cruz-Fiocruz; Brasil.Lutzomyia longipalpis s.l. is the primary vector of Leishmania (L.) infantum in the New World. In this study, male Lutzomyia longipalpis specimens from Posadas, Argentina were characterized for two polymorphic markers: the male sex pheromone and the period (per) gene. The male sex pheromone was identified as (S)-9-methylgermacrene-B, the same compound produced by Lu. longipalpis from Paraguay and many populations from Brazil. The analysis of per gene sequences revealed that the population from Argentina is significantly differentiated from previously studied Brazilian populations. Marker studies could contribute to the understanding of the distribution and spread of urban American visceral leishmaniasis, thus aiding in the design of regional surveillance and control strategies.