Vaccines were the result of trial and error research until molecular biology and genetic engineering have made the possibility of a whole new set of improved vaccines. These newer vaccines need to be inexpensive, stored and transported easily and of course easily administered. For a vaccination program to be successful especially in a developing country, all these matters a lot. Heat stable plant made or edible vaccines are inexpensive to produce, can be administered orally and enhances vaccine coverage in children, particularly in the developing countries. These edible vaccines can deliver un-degraded antigens to the enteric mucosal system. This critical review summarizes plant-derived vaccines, the mucosal immune response and its efficacy.