The causative treatment of type I allergies is a long pursued goal in immunology. To design safe and efficient vaccine preparations, the interaction of the allergen and the symptom-inducing IgE antibodies still needs to be better understood. In this article, we describe the use of the phage display technique in allergy. It yields epitope mimics, so-called mimotopes, which can be employed for both, investigation of allergen-IgE interactions and definition of safe novel vaccines.