Pollen of many grasses, trees, and weeds are the source of inhalant allergic proteins while various other plant products are allergenic only upon their ingestion as a food source. Allergenic proteins of pollen are exposed to human immune system after their rapid release from pollen upon coming in contact with moist surface of nasal mucosa. The advent of molecular cloning and ability to genetically transform plants now offer unprecedented opportunities to produce hypoallergenic plants by targeted switching off allergen production. Gene silencing strategies that operate at post-transcriptional level are highly suitable for blocking allergen production. We have demonstrated the concept of allergen gene silencing through antisense approach by producing ryegrass plants that do not produce major allergen in its pollen. Our results show the potential of antisense approach in reducing the allergenic potential of plants. Such a strategy can have a general applicability for production of transgenic plants depleted of both inhaled and ingested allergens. In addition, such an approach could also help in elucidating the in vivo function of allergen(s) in plants and contribution of an allergen to overall allergenic potential of an allergen source.