This report discusses safety issues identified during the Safety Board's special investigation of 55 emergency medical services (EMS) aircraft accidents that occurred in the United States between January 2002 and January 2005. Safety issues discussed in this report focus on less stringent requirements for EMS operations conducted without patients on board, a lack of aviation flight risk evaluation programs for EMS operations, a lack of consistent, comprehensive flight dispatch procedures for EMS operations, and no requirements to use technologies such as terrain awareness and warning systems to enhance EMS flight safety.