Sex-biased dispersal is a specific pattern of movement whereby one sex either stays or returns to its natal group or natal area to breed while the other disperses from the natal area. Temperate vespertilionid bats are thought to exhibit the typical mammalian pattern of male-biased dispersal although relatively few studies have been conducted on this group. The northern myotis (Myotis septentrionalis) is a relatively common forest dwelling bat found in eastern North America. Despite being a common species in North America, relatively little is known about its habitat requirements and life history characteristics including dispersal patterns. Using five polymorphic microsatellite loci I found that females within localized subpopulations exhibited a higher degree of genetic structuring than males indicating female philopatry and male-biased dispersal [female F_ST  =  0.011; male F_ST  =  −0.016; P  =  0.006 (sex-biased dispersal randomization test)]. I also found a weak (F_ST  =  0.002), but significant (P  =  0.03), average fixation index for the subpopulations examined which is consistent with other studies on temperate vespertilionid bats. The presence of maternity site fidelity in M. septentrionalis may have important conservation implications since commercial and private development that thins or removes potential roost trees could have an impact on pregnant female bats that will have to incur additional costs of searching for new roosting habitat as they return from their hibernacula.