Specific immunotherapy or allergen vaccination has been in routine use since 1911 for the treatment of respiratory allergic diseases. It is more effective in children and young adults than later in life. Its efficacy has been demonstrated in double-blind placebo controlled studies in both allergic rhinoconjunctivitis and allergic asthma. The improvement of allergenic extracts (in particular by standardization), the better understanding of the mechanisms of action of immunotherapy, the use of local administration routes and the publication of guidelines have legitimate its definite role to play in the therapeutic management of allergic respiratory diseases in childhood.