The implementation of a new bear management program in Yellowstone National Park in 1970 began a new era in bear-human interactions within the park. The rate of bear-inflicted human injuries decreased from 2.7/million visitors from 1970 through 1979 to 0.5/million visitors from 1980 through 1994. This was primarily due to decreased roadside injuries from black bears (Ursus americanus) as public education increased and food conditioned bears were removed from roadsides and developed areas. After 1980, the majority of injuries occurred in the backcountry. Backcountry injuries tended to be more severe and were more often caused by grizzly bears (Ursus arctos) than those that occurred along roadsides. Of the 34 injuries that occurred in the backcountry from 1970 through 1994, 13 (38%) were considered severe and 3 (9%) resulted in human fatalities. Ninety-one percent of all injuries in the backcountry involved people as they were hiking, and 9% occurred in backcountry campsites. Ninety-seven percent of the hikers injured by bears reported surprise encounters as the cause of the attack, and 68% of these incidents involved female bears with young. Most hikers that were injured (61%) reacted to encounters with bears by running or attempting to climb trees. Most (80%) hikers that resisted during bear attacks were severely injured. Backcountry injuries occurred both in forested habitat (68%) and nonforested areas (32%). Visitor and employee education on precautions to take when hiking in bear habitat may be the most useful tool in further decreasing bear-inflicted human injuries within Yellowstone National Park.