Introduction: Blood transfusion for hemorrhagic shock is standard therapy. The purpose of this study was to document the development of protocols for administering red blood cells and review the experience with inflight blood transfusions.Setting: This study was conducted at a hospital-based rotor-wing (RW) program whose service area is a large rural area in southeastern Minnesota. A BK 117 with a flight nurse/flight nurse configuration was used.Methods: The RW registry was accessed during a 3-year period (August 1993 to July 1996), and 2131 records were reviewed to retrospectively analyze blood use during transport. Blood bank records and protocols also were reviewed.Results: This helicopter program maintains a refrigerator with 4 units of O-negative blood that is kept in the hangar and serviced by the blood bank. Blood was taken on all appropriate transports (91% interfacility, 9% scene), and 94 of 2131 patients (4%) were transfused. Criteria for blood transfusion included Hgb < 10, persistent hypotension after resuscitation, and clinical signs of shock. Medical conditions consisted of trauma (48% of patients), gastrointestinal (GI) bleed (25%), abdominal aortic aneurysm (AAA) (17%), and other (10%). The mean Hgb before and after transport was 8.9 and 10.2, respectively; 38% of the patients received an average of 3 units before transport. Overall, 2 units red blood cells were given in flight and another 12 units during hospitalization. No complications occurred with blood transfusions.Conclusion: Selected RW patients will benefit from in-flight blood transfusions. Proximity of blood storage to the helicopter is mandatory to avoid delays in transport. A close working relationship with blood bank personnel ensures ready availability of current O-negative blood.