Thirteen microsatellite loci were used to address three hypotheses regarding genetic diversity in the humpback whitefish Coregonus clupeaformis complex in Alaska. The test results provided further insight into the factors influencing C. clupeaformis complex population structure and level of genetic variation. First, themicrosatellite data did not provide evidence of two spatially distinct Beringian and Eurasian refugial groups as revealed in previous phylogeographic analyses ofmitochondrialDNAvari- ation. Rather, the population structure inferred from the microsatellite variation appears to reveal the influence of factors on amore recent time scale, including gene flowamong the refugial groups and iso- lation of some anadromous and freshwater resident populations. Second, anadromous C. clupeaformis complex collections exhibited higher intra-population genetic diversity than freshwater resident col- lections. This outcome is consistent with previous meta analyses suggesting that freshwater resident populations probably have smaller historical effective population sizes and less conspecific gene flow because the habitat tends to be smaller and supports fewer and smaller populations. Finally, the analy- sis of contemporary immigration rates was consistent with, but did not provide statistical support for, the hypothesis that gene flow among anadromous C. clupeaformis complex populations along coastal Alaska is influenced by the Alaska Coastal Current. Further studies are needed to evaluate gene flow among coastal Alaska C. clupeaformis complex populations. Published