Over the past 40 years, there has been a re-orientation of virology studies toward the beneficial use of viruses, and several plant viruses have been employed as expression vectors. The use of plant virus vectors for production of recombinant proteins has advantages such as speed of expression, high yield, reduced cost and duration of studies, and an extremely high throughput of recombinant proteins.  Thus with such vectors large scale production of recombinant proteins required for pharmaceutical and industrial applications is accessible. Plant viruses can also also be used for improved vaccine efficacy. Such vaccines can be made by ligand conjugation of a non-immunogenic peptide to the outer surface of the virus coat protein. Finally, plant virus vectors can be employed as library construction tools for discovery of gene function in genomics studies. Here, we review the use of plant viruses in expression of recombinant proteins.