For most people, hymenoptera stings produce only a transient and bothersome local inflammatory reaction characterized by pain, redness and swelling. However, for those who are allergic to components of the venom, a re-sting may cause life-threatening, even fatal reactions. In such patients, correct diagnosis is a prerequisite for effective management (i.e., specific venom immunotherapy) and generally consists of appropriate skin testing and quantification of venom-specific immunoglobulin E antibodies. In spite of the high efficiency of properly administered venom immunotherapy, the molecular and cellular mechanisms of the desensitization process remain incompletely understood.