Therapeutic vaccination is the only disease modifying allergy treatment. Recombinant allergen vaccines represent defined component vaccines and are advantageous compared to allergen extract vaccines because of their well defined and measurable allergen content. As the major birch pollen allergen Bet v 1 is the dominant disease-eliciting allergen in birch pollen Bet v 1 vaccines based on GMP produced recombinant (r)Bet v 1 have been developed for treatment of birch pollen allergic patients. Three vaccines comprising hypoallergenic rBet v 1 derivatives have in clinical trials been shown to improve allergic symptoms and to favourable modify the immune response to Bet v 1. In a phase II trial, vaccination with rBet v 1 resulted in reduced rhinoconjunctivitis symptoms and rescue medication compared to placebo. Vaccination with rBet v 1 formulated as tablets for sublingual administration revealed clinical relevant efficacy in rhinoconjunctivitis patients. The positive results imply that rBet v 1 vaccines constitute a therapeutic alternative for birch pollen allergic patients.