Since 20th century, when allergy was defined, an ongoing attempt for discovering the mechanisms underlying it and its treatment began. Defining allergens as well as cells such as regulatory T-cells and characterizing the antibodies involved in the pathogenesis (including blocking antibodies) have helped very much towards a better understanding of the immunologic process. However, allergen specific immunotherapy (SIT), as a specific curative treatment for allergy also dates back to the beginning of the previous century and has progressed considerably during these years. SIT similar to natural immunomodulation, directs the immune response towards tolerance. New strategies in this field, such as using recombinant allergens, T- and B-cell-epitope-containing peptides, and DNA vaccination have shown promising results. Sublingual immunotherapy, although not yet FDA-approved, as an alternative strategy in SIT has demonstrated efficacy as well as safety. Furthermore, allergen extracts, their standardization and their modification have also been the focus of much research. Undoubtedly, specific immunotherapy is proven to be an efficacious method to treat allergy, so its cost-effectiveness should be estimated in developing countries in order to include it in the country's health priorities. Informing physicians about the new anti-vaccination movement is also crucial.