We examined genetic variability and spatial heterogeneity of maternally (mtDNA) and biparentally (allozymes) inherited genes for a large, widely distributed mammal. White-tailed deer (Odocoileus virginianus) in 6 populations from the coastal plain in Georgia and South Carolina showed high levels of variability and spatial heterogeneity for mtDNA and allozymes. There was little sharing of mtDNA variants among samples separated by 30 to 100 km, and 12 of 13 allozyme loci showed significant differentiation among populations. Spatial genetic heterogeneity was positively correlated with geographical distance as predicted in Wright's isolation by distance model. High spatial heterogeneity is surprising considering the species' physical capacity for moving great distances. Dispersal must be limited, but more so in females because they accounted for only an estimated 13% of total dispersal. Social factors must strongly limit dispersal in white-tailed deer and probably many other mammals.