In the last two decades, preparation of infectious RNA or DNA clones of plant viruses has transformed to a standard laboratory technique, providing an excellent tool for the research of viral gene functions and virus-host interactions. A full-length clone can be transformed in vitro to a viral vector expressing foreign poly/oligopeptides in soluble form or fused to a viral capsid protein. The use of the plants as producers of antigens, allergens, and other pharmaceuticals is cheaper than the use other eukaryotic bioreactors. Transient expression of proteins using the vector technique has several advantages in comparison with a transgenic approach. Virus-induced gene silencing vectors have been widely adapted for research of plant genes functions and screening of plant genomes for resistance genes. The potential instability of the constructs remains the main problem of virus vector-based techniques leading to a wild-type virus recovery by recombination. A novel approach including "a deconstructed virus-strategy" may overcome these difficulties. A preparative-scale production of numerous biologically active compounds in the various plants using viral vectors are expected in the near future.