Studies on the vertical stratification of phlebotomine sandfly fauna were conducted in a non-flooded primary forest at a Tropical Forest Experimental Station of the National Institute of Amazonian Research from October 1998 to March 1999. CDC light traps were placed at one, 10, and 20 meters above ground. A total of 2,859 sandflies were captured, belonging to the Lutzomyia (99.93%) and Brumtomyia (0.07%) genera, represented by 38 species. In the Lutzomyia gender, the most frequent sub-gender was Nyssomyia (43.4%), followed by Psychodopygus (22.8%). Lutzomyia umbratilis, L. anduzei, L. rorotaensis, L. trichopyga, and L. olmeca nociva predominated at one meter above ground, while L. davisi, L. infraspinosa, L. umbratilis, L. trichopyga, and L. anduzei predominated at 10 meters. L. anduzei, L. tuberculata, L. dendrophyla, and L. dreisbachi were the most abundant species at 20 meters. L. umbratilis, which appeared at all three levels of vertical stratification, has great epidemic significance as a vector of Leishmania (Viannia) guyanensis.