The classification of American Phlebotominae is particularly difficult as many species are known in one sex only, because of the large number of species and their great morphological variation, without, however, the formation of clearly defined groups. The relative importance of the morphological characters was studied. Morphological and histological studies of the spermathecae have shown that segmentation is the result of a system of muscles which compress the spermatheca for the expulsion of sperm. The results are correlated with the classification of Old World Phlebotominae and a general classification of the family established. A provisional classification of the American species is proposed.