The chromosome numbers of the eight following species of freshwater diaptomid copepods were examined to elucidate relationships between species: Aglaodiaptomus clavipes, A. leptoups, Leptodiaptomus ashlandi, A. minutus, A. sicilis, A. siciloides, Skistodiaptomus oregonensis, and S. pallidus. The specimens evaluates were collected from various lakes in Wisconsin including Lake Michigan. Squash mounts were prepared from female individuals for microscopic evaluation. Comparisons of chromosome numbers and chromosome morphology indicated that the species considered are not as closely related as might be suspected based on external morphological considerations. The chromosome numbers varied greatly between species and no consistant numbers within subgenera were observed, substantiating the idea that the species are clearly well separated phylogenetically. A technique for preparing chromosome squash mounts from formalin preserved specimens in presented.Ball State UniversityMuncie, IN 47306