Objective.—To describe the general characteristics and epidemiology of search and rescue (SAR) in Yosemite National Park (YNP) and identify possible areas for intervention directed at reduction in use of these services.

Methods.—Yosemite Search and Rescue (YOSAR) personnel record every search and rescue mission on a Search and Rescue Incident Report. The information contained in these reports was used to perform a retrospective review of all SAR missions within YNP during the 10-year study period between January 1990 and December 1999.

Results.—YOSAR performed 1912 SAR missions, assisting 2327 individuals and recording 2077 injuries and illnesses. Popular trails in and around Yosemite Valley collectively accounted for 25% of all individuals needing SAR services. Lower extremity injuries and dehydration/hypovolemia/hunger were commonly identified reasons to need SAR services. The duration of SAR missions averaged 5 hours, used 12 SAR personnel, and cost $4400. Helicopter was the primary mode of transport in 28% of SAR incidents. There were 112 fatalities, yielding a SAR case fatality rate of 4.8%. The majority of fatalities occurred while hiking/snowshoeing, with falling the most common mechanism of lethal injury.

Conclusions.—Day-hikers in and around Yosemite Valley use a large portion of SAR services, with lower extremity injuries and dehydration/hypovolemia/hunger the most common reasons. It seems reasonable to direct future intervention to prevention of these commonly identified problems in this particular population of Park visitors.