Vaccination is a great asset for eradication of infectious diseases in humans and animals. With the prevalence of antibiotic resistant bacterial strains and an alarming increase in new and re-emerging pathogens, the need for vaccination continues to be a high priority for mammalian diseases. In the last several years, a novel approach for developing improved mucosal subunit vaccines has emerged by exploiting the use of genetically modified plants. It has been demonstrated that plant-derived antigens are functionally similar to conventional vaccines and can induce neutralizing antibodies in mammalian hosts. Using genetically engineered plants for the production of immunogenic peptides also provides a new approach for the delivery of a plant-based subunit vaccine, i.e., oral delivery, provided these immunogenic peptides are expressed in an edible part of the plant, such as grain or fruit. Thus, food crops can play a significant new role in promoting human health by serving as vehicles for both production and delivery of vaccine.