A review of the known geographical distribution and current knowledge on the genetic popu-lation structure of harbour seals (Phoca vitulina) in the North Atlantic is presented. Based on a synthesis of the results from five different studies of neutral genetic markers (mtDNA and nuclear microsatellites, mainly) twelve genetically distinct populations were identified in the North Atlantic: USA/Canada, Iceland, west coast of Norway, Ireland-Scotland, English east coast, Channel area, Wadden Sea, Limfjord, Skagerrak, Kattegat, West Baltic, and East Baltic. Most of the studies addressed the population structure at the regional level, while only a few addressed the structuring at a local level, i.e. within countries. Due to the limited number of studies con-ducted, the identified population units were considered preliminary and more detailed, local stud-ies would probably reveal structuring on a finer scale. The choice of genetic markers, their prop-erties, resolution in time and applicability in population structure studies is shortly discussed and compared to ecological methods used to delineate populations.