Encontramos abundantes promastigotas nos tubos de Malpighi, além do tubo digestivo, em elevada proporção de fêmeas de Lutzomyia longipalpis experimentalmente infectadas em hamster inoculado com Leishmania mexicana amazonensis.As a preparatory stage for a study aiming at identifying the species and subspecies of local Leishmania in naturally infected sandflies through immunoradiometric assay with monoclonal antibodies, we tried to obtain experimental infections of phlebotomines with well characterized stocks of parasites, in order to test the effectiveness of the method.