The extent of genetic variation and its geographic structure as revealed by mitochondrial DNA (mtDNA) analysis are reviewed for five percid species. Walleye(Stizostedion vitreum)has been the most studied species and extensive polymorphism (42 haplotypes) was found in whole‐molecule RFLP studies, with significant geographic structure to the distribution of the haplotypes being largely related to Pleistocene glacial events. Analysis of whole‐molecule mtDNA with 4‐and 5‐base recognition restriction enzymes also revealed considerable variation which permitted the discrimination of individual fish from two central Great Lakes populations. DNA sequencing and PCR‐RFLP studies have also revealed high levels of mtDNA variation in walleye and provided better resolution of population‐level heterogeneity. In contrast, sauger(S. canadense)shows very little mtDNA variation (only five haplotypes) with little geographic structure to the haplotype distribution. There is also no clear geographic structure to mtDNA variation in yellow perch (Perca flavescens)where 15 haplotypes have been identified. Preliminary data for Eurasian perch(P. fluviatilis)(five haplotypes) and zander(S. lucioperca)(three haplotypes) reveal some mtDNA polymorphism in both species, but sample sizes are too small in both cases to make any statements about their geographic structure.