This study is designed to give additional information on the efficacy, safety and local effects (tolerability) of a dose of sublingual immunotherapy administered once a day, during a second grass pollen season.

Allergy is one of the most common chronic diseases. Allergies to grass, weed, and tree pollens characteristically result in seasonal rhinitis symptoms commonly termed hay fever. The risk of developing asthma has been noted to be higher in patients with rhinitis than among the general population (10% versus 3.6%), confirming the fact that rhinitis is often the first step of the natural history of asthma.

Although several drugs effectively manage the symptoms of allergic rhinitis, conjunctivitis or asthma, they do not represent an etiopathogenic treatment of the considered diseases, and do not prevent the reappearance of the symptoms at the end of the treatment.

Immunotherapy is generally considered to be appropriate for patients in whom rhinitis symptoms cannot be controlled by an optimal medication regimen and avoidance of the allergens. At present, specific immunotherapy is the only therapy available that acts on the main cause of the allergic reaction by modifying or down-regulating the immune response.

Allergen immunotherapy is the administration of gradually increasing quantities of an allergen vaccine (extract) to an allergic subject, to reach a maintenance dose, which is effective in reducing the symptoms associated with exposure to the causative allergen.

Inclusion Criteria:

• Patients who meet the in and exclusion criteria for study AB0602 and successfully finished this study.
• Patients who have given their written consent to participate in this study.
• Patients who are willing to comply with the protocol and understand the information given.
• Female patients of childbearing potential are eligible if they are not sexually active or if they use a medically accepted contraceptive method.
• Negative urine pregnancy test if female at the end of the previous study.

Exclusion Criteria:

• Pregnancy, breast-feeding / lactation or sexually active women of childbearing potential who are not using a medically accepted contraceptive method.
• Patients who were non-compliant during study AB0602.
• Patients with a past or current disease, which as judged by the investigator, may affect the patient's participation in or the outcome of this study.