Remains of a woolly mammoth (Mammuthus primigenius) were found in Qagnaxˆ Cave, a lava tube cave on St. Paul Island in the Pribilof Islands, 500 km west of the Alaskan mainland in the Bering Sea. Several dates converge on 5725 14C yr BP, making these the youngest mammoth remains discovered in North America, and among the few Holocene mammoths known. Genetic analysis of the cytochrome b gene and adjacent regions of the mitochondrial genome demonstrates that the Qagnaxˆ mammoth is highly derived, possessing several unique polymorphisms not found in other mammoths. However, while this is consistent with a recent insular isolation scenario, phylogenetic analysis suggests that the specimen represents a population whose isolation from other mammoths occurred at or well before the terminal Pleistocene submergence of the Bering Land Bridge. It is possible that it represents a member of a “land bridge subclade” of woolly mammoths that remained distinct from mainland Alaskan populations, but was not restricted to highland areas until the land bridge was submerged. Additional eastern Beringian, and particularly insular, mammoth DNA sequences are required to explore this possibility.