Recently, a new Leishmania amazonensis focus was described in a sub-Andean region (1,450-2,100 meters above sea level) of Bolivia. In this area, three anthropophilic sandfly species were identified: Lutzomyia nuneztovari anglesi Le Pont & Desjeux, 1984, which represented 86-99% of the captures, Lu. galatiae Le Pont et al., 1998, and Lu. shannoni Dyar 1929. Only Lu. nuneztovari anglesi was found naturally infected by flagellates (16 of 1,715 females). Three Leishmania stocks were isolated and analyzed by isoenzyme electrophoresis at 11 loci. No significant isoenzymatic differences were demonstrated between them and 7 stocks isolated from patients from the same area, and previously characterized as L. amazonensis. Moreover, in a simplified protocol, the experimental infection of Lu. nuneztovari anglesi by L. amazonensis was successful in 92% of the surviving specimens. These data are discussed in relation to the Killick-Kendrick criteria. These results strongly suggest that Lu. nuneztovari anglesi is the vector of L amazonensis at Cajuata, Inquisivi, La Paz, Bolivia.