Constant emergence of diseases, along with the expanding size of world population creates demands for newer vaccines which can meet the challenges that conventional vaccines have not been able to overcome. The application of transgenic plants in the production of pharmaceuticals has led to the new approach of plant-based, orally-delivered vaccines. In recent years a number of recombinant vaccine antigens have been expressed in different plant tissues. The review highlights the generation of edible vaccines, their mode of action and their clinical application in various human diseases. Though the road ahead seems promising, there are several constraints which restrict the success and public acceptability of these vaccines. These include problems of choice of plants, storage, delivery, dosage, safety, public perception, quality control and licensing.

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