This article reviews the international literature on the cost-effectiveness of immunotherapy for respiratory allergy. Included studies conducted an economic evaluation of immunotherapy for allergic rhinoconjunctivitis, allergic conjunctivitis, allergic rhinitis, asthma or allergic rhinitis in combination with asthma. Although there were few economic evaluations and these suffered from methodological shortcomings, the evidence appears to support the cost-effectiveness of immunotherapy as compared with pharmacotherapy for allergic rhinoconjunctivitis, subcutaneous immunotherapy as compared with pharmacotherapy for allergic rhinitis and immunotherapy as compared with pharmacotherapy for allergic rhinitis and asthma. One economic evaluation suggested that immunotherapy as compared with pharmacotherapy is unlikely to be cost-effective for asthma. The questions of the cost-effectiveness of sublingual vs subcutaneous immunotherapy and of the cost-effectiveness of immunotherapy for allergic conjunctivitis have not been resolved to date. The cost-effectiveness of immunotherapy depends on the duration of the clinical benefit of immunotherapy following treatment cessation, and on the break-even point of cumulative costs between immunotherapy and pharmacotherapy. There is a need for economic evaluations based on high-quality prospective and long-term clinical studies comparing immunotherapy with pharmacotherapy in real-life practice and comparing sublingual with subcutaneous immunotherapy.