Plants are an economic and easily scalable production system for the production of proteins of agricultural, pharmaceutical and industrial interest with minimal risk of contaminations with animal pathogens. The plastid genome represents an attractive target of genetic engineering in crop plants owed to its small size and abundant number of plastids in a single plant cell. The genetic modifications of the plastid genome, therefore, have recently emerged as an alternative for the expression of different proteins. Compared with nuclear transformation, plastid genetic engineering offers unique advantages which have stirred enormous interest among plant biotechnologists. Plastid genetic engineering is, particularly more suitable for the use of plants as biofactories. Higher plants have been proposed as an economic, safe and easily scalable production system. Several recombinant proteins have been expressed using plastid transformation, including therapeutic proteins, antibiotics, proteins with immunological properties and enzymes. In addition, plastid genetic engineering has been used for metabolic engineering of numerous pathways as well as for the expression of insecticidal toxins.