The study drug is a sublingual immunotherapy (vaccine) with allergenic extract of grass pollen (Lolium perenne (50%) + Cynodon dactylon (50%)). Sublingual immunotherapy has been available on the European market to treat patients with allergic rhinoconjunctivitis (itching, sneezing, stuffy nose, runny nose) for many years. In this study it will be used as drops under the tongue. At the beginning of the study, you will be given a card that documents that you are taking part. Please carry this with you at all times, in case treatment is necessary at another location. The drops will be given at two doses. The drops are held under the tongue for 2 minutes prior to swallowing.Sublingual Immunotherapy has been shown to be safe and effective in reducing the symptoms of allergic rhinoconjunctivitis (nasal allergy and allergy of the eyes).