Objective.—Outdoor-related activity has been on the rise in recent years, and hiking and backpacking are among those activities with the largest growth in participation. As the number of participants with varying experience increases, it is expected that there will be an increase in injuries related to these activities. Little empirical data exist related to outdoor injury types and rates. Our objectives were to determine incidence and frequency of injuries related to outdoor activity and requiring emergency medical system (EMS) activation at a national park.

Methods.—This retrospective study examines injuries within Yellowstone National Park. Subjects were selected from a database containing all EMS calls within Yellowstone National Park from calendar year 2003 through 2004. Data collected included age, gender, type of injury, location, activity at the time of injury, and EMS response.

Results.—There were 306 injuries reviewed. The mean age of patients was 40.9 years (SD: 23.0), and the group comprised 49.0% males. Emergency medical system transport was not required in 59.2% of injuries, and of those transported, 58.4% of patients required basic life support only. Of all injuries, 77.4% involved soft tissue, including lacerations. Hiking and walking accounted for 38.0% of all injuries, and 56.0% of those injuries involved the lower extremity. Only 8.8% of the injuries involved fractures and/or dislocations.

Conclusions.—In this study of EMS responses at a national park, the majority of injuries sustained were minor in nature. More than one third of injuries occurred while patients were hiking or walking, and most of those injuries involved the lower extremity. These results will help optimize resource planning in the national park setting.