Lutzomyia longipalpis is reported for the second time after 50 years in Misiones Province, Argentina. This insect is the vector of Leishmania (L.) chagasi, visceral leishmaniasis' parasite. The literature concerning the 16 visceral leishmaniasis cases in the country is reviewed. The cases were reported from Salta, Jujuy, Santiago del Estero and Chaco Provinces. Based on the clinical and entomo-epidemiological data two alternative hypotheses were evaluated: a) visceral leishmaniasis in Argentina is due to the visceralization of L. (V.) braziliensis or their variants, b) L (L.) chagasi remains in enzootic foci where the human contact is very unusual. Recommendations concerning the management of new cases have been made in order to confirm either one or both hypotheses. In consequence, the appropriate diagnosis and therapy could be arrived at according to the parasite actual identity, and the risk of outbreaks and mitigation measures could be estimated.