The present number of publications an allergen specific immunotherapy (ITa) by clinically controlled tests, double blind, is objective proof of the value of this treatment in the allergy pathologies mediated by IgE. The mechanisms of action of Ita are better understood, taking account of the intervention of TH2 and TH1 cells with the respective involvement of cytokines IL4-IL5, favouring the synthesis of IgE and interferon gamma (IFN gamma) slowing the synthesis of IgE. Adjuvants of bacterial origin influence the balance TH2/TH1 by blocking the production of TH2 cells. Ita by the sublingual route (SLIT) has been the objective of double blind clinical studies, with favourable results and good tolerance, of a number of allergens, pollens (grass, ragweed, parietaria, olive) and D. pteronyssinus mites. Application of this technique of SLIT to foods and drugs reveals more a mechanism of customisation than induction of cellular acticity, of a mucosal secretory IgA and an oral tolerance with systemic response, mechanisms that are involved in SLIT. Taking into account the restrictions of ITa, SLIT allows inclusion of other allergic patients, such as children receiving injections and subjects who are not inclined to observe and comply with treatment.... The different techniques used for classical ITa by the subcutaneous route are also useable for SLIT with a very good tolerance, apart from some transitory digestive problems. SLIT is no longer a technique of the future, but already one of the present time, currently used and which gives a renewal of value in the form of therapy that is ITa for IgE-mediated allergy pathology.