Allergen specific immunotherapy (ASI) is a well-documented treatment for allergic asthma, rhinitis and allergy to bee venoms. Immunotherapy with subcutaneous injections of allergens extracts has proved beneficial in reducing symptoms of allergic rhinitis and asthma. Side effects due to specific immunotherapy in short term have been largely documented. These effects were various but were usually mild. Fatal reactions are less frequent. We reported a case of a woman, with a history of allergic asthma under specific desensitization protocol who developed an acute multi-organ failure (MOF) consecutive to administration of ASI (Alustal(®) Stallergenes SA, France). This fatal reaction has never been described as adverse event of specific immunotherapy. We aimed to describe this dramatic reaction, expose the arguments to define the relationship between the administration of allergen extract and the occurrence of this fatal reaction.