Type I hypersensitivity reactions are in constant progression in industrialized countries. The physiopathologic mechanism of these diseases implicates the production of specific immunoglobulin (Ig)E to allergenic molecules, their binding to the Fcepsilon receptor on the surface of mast cells and basophils, and the release of inflammatory mediators when allergens are introduced into the body and crosslink with the IgE bound to the cell surface. An allergen is defined as a molecule that induces the production of, and binds to, IgE. The identification of the allergenic molecules is an important goal to improve diagnosis and treatment of allergy. This characterization aims to extract proteins from the allergenic source, to analyze IgE specificity by immunoblotting and to identify the proteins that bind IgE.