A novel humanized anti IgE antibody is disclosed. The antibody is capable of binding to free IgE membrane bound IgE on B lymphocytes IgE bound by CD23 but not to IgE bound by high affinity IgE.Fc receptor on mast cells. The present invention relates to the treatment of IgE mediated diseases including allergic asthma allergic rhinitis atopic dermatitis food allergy chronic spontaneous (idiopathic) urticaria chronic rhinosinusitis systemic mastocytosis cutaneous mastocytosis allergic bronchopulmonary aspergillosis recurrent idiopathic angioedema and eosinophil associated gastrointestinal disorder by administering the anti IgE antibody of the present invention.