Beetles of the genus Mordellistena Costa are submitted to a morphometric analysis as a more feasible method of identification and as a foundation for the construction of a phylogeny. In the past, species groups were based on questionable morphological characters and a morphological analysis is an attempt, through numerical methods, to eliminate such doubts. Thirty external characters were chosen for measurement in a preliminary statistical analysis of four well defined species groups. These results were submitted to a discriminant analysis which reduced the number of significant characters to 14. Over 500 specimens were then measured for these characters and the results were then submitted to a cluster analysis. The results of the analysis illuminated several relationships among the genus. The analysis found 14 major groups (five or more members), 25 minor groups (4 or fewer members), and 102 odd specimens not assigned to any group. The major groups, two of the minor groups, and the 102 odd specimens are discussed in detail. The accomplishments of the study included an expansion of the list of species of Mordellistena for Arizona, the discovery of several previously undescribed species, a more confident method of identification, and the foundation of a phylogeny for the genus. Shortcomings of the study were the failure to construct species specific groups and failure to group 102 specimens. Both successes and failures of the study are discussed in detail and explanations are offered. The major successes of the study were the formation of a basis for a complete revision of the genus Mordellistena and the foundation of a phylogeny for the group.