Atopic disease affects approximately 30% of the population in western society. Allergen-specific immunotherapy (SIT) is the only treatment with a long-term effect available at the present time, and has been used successfully in the treatment of a number of allergies for almost 100 years. Despite this success, there is great demand for safer, faster and more effective approaches. At present, many studies are being conducted aiming to comply with this demand. The approaches used include conventional immunotherapy, using allergen extracts, as well as novel methods such as peptide immunotherapy, allergen DNA vaccines and non-injection routes of SIT. The clinical success of various treatments, new technical developments and a better understanding of the immunological mechanisms behind immunotherapy hold great potential for the broad application of allergen-SIT in the foreseeable future.