Twenty-seven patients with severe anaphylactic reactions were treated by two anesthesiologist-staffed ambulance helicopters during a 5-year period. All patients had signs of respiratory and/or circulatory failure. Cutaneous symptoms were described in 70% of the patients, gastrointestinal symptoms in 30% and central nervous symptoms in 85%. Wasp sting and drugs were the most common causes. Other etiologies were bee sting, snakebite, nuts and exercise. All patients were provided with advanced pre-hospital medical care. Epinephrine was employed in 78% of the patients. I.v. fluid therapy was started in 77%. Three patients (11%) needed endotracheal intubation. The time-span from onset of symptoms to medical attendance exceeded 45 min in two patients; both died. Of the surviving patients, 23 were hospitalized. The majority had no signs of respiratory or circulatory failure on arrival in the emergency room and needed only observation in the hospital.