This study investigates the safety of two up-dosing regimen. The safety of PURETHAL Birch will be evaluated in a rush regimen (maximum dose reached in 3 injections during 3 weeks) compared to the conventional regimen (maximum dose reached in 6 injections during 6 weeks).

The primary endpoint of the sudy is the comparison of the proportions of the patients who have successfully reached the maintenance dose between the two treatment regimes.

A similar previous study with PURETHAL Grasses has shown that the rush up-dosing scheme is as safe as the conventional up-dosing regime. Therefore it is expected that up-dosing with PURETHAL Birch according to the rush regimen is as safe as using the conventional regimen.

Inclusion Criteria:

• Signed informed consent.
• Age ≥12 years.
• Allergic rhinitis/rhinoconjunctivitis related to birch pollen with or without concomitant mild to moderate persistent asthma
• FEV1>70% for patients with a history of mild to moderate asthma, FEV1>70% or PEF>80% for patients without a history of asthma
• A positive SPT (mean wheal diameter ≥ 3mm compared to negative control and negative control should be negative) for birch pollen.
• Positive serum specific anti-birch IgE-test (>0.7 U/ml) within 1 year before randomization and/or a positive provocation test for birch pollen within 1 year before randomization.

Exclusion Criteria:

• Immunotherapy (SCIT or SLIT) with birch pollen allergens within the past 5 years
• Any specific immunotherapy (SCIT or SLIT) during the study period
• Severe immune disorders (including auto-immune diseases) and/or diseases requiring immunosuppressive drugs
• Active malignancies or any malignant disease within the past 5 years
• Severe uncontrolled diseases that could increase the risk for patients participating in the study
• Acute/active inflammation or infection of the target organs at the start of the study
• Secondary changes of the target organ
• Diseases with a contraindication for the use of adrenaline
• Use of systemic steroids within 4 weeks before start of the study and during the study
• Treatment with systemic and local β-blockers
• Vaccination within one week before start of therapy or during the initiation phase
• Anti-IgE therapy within the 6 months prior to inclusion and during the study
• Participation in a clinical study with a new investigational drug within the last 3 months or for a biological within the last 6 months prior to or during the study
• Pregnancy, lactation or inadequate contraceptive measures for women of child-bearing age
• Alcohol, drug or medication abuse within the past year
• Any clinically significant abnormal laboratory parameter at screening
• Lack or expected lack of cooperation or compliance
• Severe psychiatric, psychological, or neurological disorders
• Patients who are employees of the sponsor, institution or 1st grade relatives or partners of the investigator