One such novel technology is nanotechnology, which has been revolutionized in health care, textile, materials, information and communication technology, and energy sectors too. There are many ways depicted in various literatures to synthesize silver nanoparticles. These include physical, chemical, and biological methods. The physical and chemical methods are numerous in number, and many of these methods are expensive or use toxic substances which are major factors that make them “not so favored” methods of synthesis. An alternate, feasible method to synthesize silver nanoparticles is to employ biological methods of using microbes and plants. Biotechnology has considered a safe agricultural tool to enhance crop protection, subsequently to produce more agricultural products, improve food process, nutritional value, and better flavor. Side by side it has detrimental ecological consequences such as spreading genetically engineered genes to indigenous plants, elevated toxicity, which may transmit through food chain, disrupting nature’s system of pest control, developing new weeds or virus strains, biodiversity loss, and insecticidal resistance (Goswami et al., 2010). Hence, it is necessary to bring forth new innovative technology/methods to overcome the above mentioned problems. The potential application of biogenic nanoparticles as antimicrobial agents will be also reviewed. The mechanism of action of nanoparticles as bactericidal and antifungal agents will be highlighted in this chapter.