the appearance of the vector of visceral leishmaniasis (vl) lutzomyia longipalpis in the province of formosa in 2004 was associated with urban epidemic risk for the first time in argentina. during 2006, vectors, canine and human cases of vl were reported in the province of misiones, and in summer 2008-2009, in the province of corrientes. in santiago del estero province in 2008, cases of human and canine vl were associated with secondary vectors. therefore, with the aim to know the current distribution of vl risk in the chaco region, systematic captures of the vector were performed between january and april 2010 in 30 localities of formosa and chaco, and in the city of reconquista, province of santa fe (224 traps/night). lu. longipalpis was reported for the first time in the cities of resistencia and puerto antequera (chaco). clorinda and puerto pilcomayo (formosa) are the localities where the traps with more individuals were obtained, 158 and 241 lu. longipalpis trap / site / night respectively. these results showed that the vector of urban epidemic vl is still spreading in argentina, and already reached the province of chaco. sporadic cases reported in the chaco region, transmitted by secondary vectors as lu. migonei would also increase due to intensified surveillance, and the dispersion of the parasite associated with the transit of asymptomatic or symptomatic infected dogs.