The study was terminated due to the interim Analysis results indicating a weaker correlation than anticipated and reported by other study groups.

The study will explore how allergy symptoms experienced during the grass pollen season compare to symptoms experienced in the Environmental Exposure Chamber (EEC).

There are 2 treatments in this study. Both treatments are injected under the skin. Allergovit® Grasses works by helping the body's immune system get used to grass-pollen before the grass pollen season begins which may lead to decreased sensitivity and reduced allergy symptoms during the grass season. Placebo treatment does not contain grass pollen mixture, and is not expected to reduce allergic symptoms overtime.

This is a Phase II trial, with a one year observational/baseline phase followed by a one year double-blind placebo-controlled, randomized, treatment phase. Approx. 137 grass pollen-allergic subjects and 20 non-allergic subjects will be enrolled in the baseline phase of the study. The primary objective of the trial is to investigate the relationship between allergy symptoms experienced by subjects (allergic and non-allergic) upon exposure to grass pollen-allergen in the EEC and the allergy symptoms experienced by subjects during the grass pollen season.

Inclusion Criteria:

• IgE-mediated seasonal allergic rhinitis/rhinoconjunctivitis with or without allergic asthma
• positive skin prick test
• specific IgE ≥ 0.70 kU/L to mixture of grass pollen allergens
• symptom score of at least 4 per day during the week following the peak-pollen count in the baseline season

Exclusion Criteria:

• undergone previous specific immunotherapy with grass pollen allergens in any formulation less than 5 years prior to the screening date
• currently undergoing any sort of immunotherapy, or has ever undergone specific immunotherapy with unknown allergen
• allergens which are expected to interfere with the grass pollen season
• uncontrolled or partly controlled asthma
• patients with contraindications for SIT