The green synthesis of metallic nanoparticles is an active area of academic and more importantly, Âapplication researchÂ in nanotechnology. A variety of chemical and physical procedures could be used for synthesis of metallic nanoparticles. However, these methods are fraught with many problems including use of toxic solvents, generation of hazardous by-products, and high energy consumption. Accordingly, there is an essential need to develop environmentally benign procedures for synthesis of metallic nanoparticles. A promising approach to achieve this objective is to exploit the array of biological resources in nature. Indeed, over the past several years, plants bacteria and fungi have been used for production of low-cost, energy-efficient, and nontoxic metallic nanoparticles. In this review, we provide an overview of various reports of Biosynthesis of metallic nanoparticles using inactivated plant biomass, living plants, bacteria and fungi.