The genetic relationships among morphologically and geographically divergent populations of whitefish (genus: Coregonus) from Denmark and the Baltic Sea region were studied by analysis of microsatellites and polymerase chain reaction- restriction fragment length polymorphism (PCR-RFLP) analysis of mitochondrial DNA (mtDNA) segments, The endangered North Sea houting (classified as C. oxyrhynchus) differs morphologically and physiologically from other Danish whitefish (C. lavaretus). However, limited divergence of North Sea houting was observed both at the level of mtDNA and microsatellites. The implications of these results for the conservation status of North Sea houting are discussed in the light of current definitions of evolutionary significant units. Both mtDNA and microsatellite data indicated that postglacial recolonization by C. lavaretus in Denmark was less likely to have taken place from the Baltic Sea. Instead, the data suggested a recent common origin of all Danish whitefish populations, including North Sea houting, probably by recolonization via the postglacial Elbe River system. Estimates of genetic differentiation among populations based on mtDNA and microsatellites were qualitatively different. In addition, for both classes of markers analyses of genetic differentiation yielded different results, depending on whether molecular distances between alleles or haplotypes were included.