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A population of muskoxen (Ovibos moschatus), successfully restored to northeastern Alaska in the 1970's, has become a source of food for grizzly bears (Ursus arctos). We tested whether grizzly bear predation on this population of muskoxen increased over time and described multiple kills of muskoxen by grizzly bears. We identified bear-muskox events from data collected between April 1982 and June 2001 during bear and muskox surveys and radiorelocation flights and from field notes, mortality records of radiocollared muskoxen, and other observations made by biologists, pilots, and local residents. Ninety-two bear-muskox events observed in 1982-2001 included 46 known kills, 37 possible kills or scavenging events, and 9 chases. Ten of 61 radiocollared muskoxen that died between 1982 and 2001 were killed by bears and 14 others were possibly killed or scavenged. The number of known kills and possible kills or scavenging increased significantly over time. Multiple kills, where 2 or more muskoxen were killed from a group, contributed to the number of known kills. Twenty-eight of 46 muskoxen (61%) killed by bears died during multiple kills. Twenty-two of these deaths occurred in 1998-2001. Ten marked grizzly bears were implicated in single or multiple kills, suggesting that several bears in northeastern Alaska became proficient predators of muskoxen in spite of the group-defensive behavior and formidable horns of muskoxen. The low numbers of muskox calves observed in 2000 and 2001 (<5 calves/100 females >2 years of age) may be due in part to predation of neonatal calves by grizzly bears. The successful return of muskoxen to northeastern Alaska has created a predictable source of large mammal protein for some grizzly bears.