Mitochondrial DNA (mtDNA) control region sequences were analysed to determine the geographical genetic structure of Hippotragus niger (sable antelope) and H. equinus (roan antelope). Analyses by AMOVA, minimum evolution networks, parsimony, neighbour joining and maximum likelihood show that the roan antelope populations are geographically partitioned and that their phylogeography corresponds well with subspecific boundaries. In sharp contrast, however, our sequence data group all the sable antelope into two well-delineated maternal clades. One comprising specimens from the strictly east African H.n. roosevelti, and a second geographically diverse group which includes H.n. niger (South Africa, Zimbabwe), H.n. variani (Angola), and H.n. kirkii (Zambia, Malawi). The differences in the genetic population structure suggest that distinct extrinsic and intrinsic factors have shaped the phylogeography of these two closely related antelope species. In the absence of obvious extrinsic barriers to gene flow, we suggest that behavioural differences may be responsible, at least in part, for the contrasting spatial patterns detected among geographical localities. Although our data reflect only the maternal phylogeny of these important game species, they nonetheless suggest that different management strategies should be applied. We recommend that roan antelope be translocated only within the currently defined subspecies boundaries, while in the case of sable antelope, conservation measures should focus on preserving the genetic integrity of the east African and southern African sable populations. Implicit in this is that translocations of animals between populations comprising these two distinct maternal genetic clades should be actively discouraged.