The Kiputz IX site has provided one of the best-preserved late Pleistocene bison populations in the southern Pyrenees and has yielded the first almost complete skull of a steppe bison (Bison priscus) in the Iberian Peninsula. This Bison priscus skull is compared on morphological and osteometric grounds with other specimens of steppe bison from Europe and North America. The skull from Kiputz IX falls within the range of the extinct subspecies Bison priscus mediator. Available data support the evidence of three chronological subspecies of Bison priscus (Bison priscus gigas, Bison priscus priscus, and Bison priscus mediator) during the Middle and late Pleistocene.