SUBLIVAC® Birch PROBE Study

Inclusion Criteria: * Subjects with allergic rhinoconjunctivitis with or without mild asthma (FEV1 ≥ 70%) due to birch pollen for at least 2 years. * Use of anti-allergy symptomatic medication in the last birch pollen season (in case of a season with low pollen counts, in one of the two previous years). * No seasonal allergic complaints induced by birch, grasses or mugwort pollen for at least 4 weeks in the absence of rescue medication during at least the last 2 weeks before the baseline. * A positive SPT (diameter ≥3 mm) for birch pollen and a positive specific serum anti birch IgE-test (\>1 U/ml). * A positive TNPT with a birch allergen extract containing a concentration of 10, 100 or 1000 AU/ml at the baseline visit. * Age 18 years and older. * Subjects shall give a written informed consent. Exclusion Criteria: * A positive SPT (diameter ≥ 3mm) for hazel or alder and the maintenance dose will not be reached before 8 October 2009. * A positive SPT (diameter ≥ 3mm) for pets and symptoms related to concomitant sensitization to pets while having these animals at home. * A positive SPT (diameter ≥ 3mm) for house dust mite or moulds and clinically relevant symptoms related to concomitant sensitization to house dust mite or moulds, based on the investigator's research (TNPT for example). * Allergy to any of the excipients of SUBLIVAC Birch or Staloral Birch. * Chronic asthma or emphysema, particularly with an FEV1 \< 70 % of predicted value or use of inhalation corticosteroids outside grass and tree pollen season for more than two episodes and/or longer than fourteen days. * Specific findings for nose and mouth at screening or rhinoscopy before TNPT. * Serious immuno-pathological diseases or malignancies (including auto-immune diseases, tuberculosis, HIV). * Inflammation or infection of the target organ (nose, eyes and lungs). * Severe atopic dermatitis requiring systemic immuno-suppressive medication. * Allergen specific immunotherapy treatment for a period longer than 3 months within the last 5 years. * History of life threatening anaphylactic events, including anaphylactic food allergy, insect venom anaphylaxis, exercise or drug induced anaphylaxis. * A positive pregnancy test, lactation or inadequate contraceptive measures. (adequate measures: oral contraceptives, IUD, condom use and having no sexual relationship with a man) * Alcohol- or drug abuse. * Lack of co-operation or severe psychological disorders. * Completed or ongoing long-term treatment with tranquilizer or psycho active drugs. * Low compliance or inability to understand instructions/study documents * Completed or ongoing treatment with anti-IgE-antibody * Patients being in any relationship or dependence with the sponsor or investigator