Progress in science is making life easy; nanoparticles are one of the modern achievements approaching social benefits in biomedical, agriculture, energy, industrial etc. Nano-drugs, nano-fertilizer, green synthesized nano-particles of antimicrobials, antioxidants and anticancerous agents are some examples. Conventionally, these are produced by chemicals; therefore, the products may be costly, limited, and nonenvironmentally friendly. Among the various alternatives nano particle-based molecules play an important role to overcome these problems. The natural content of the medicinal plants can be transferred as medicine by various methods like allopathic, Ayurvedic, homeopathic, and food. By the synthesis of nanoparticle natural content of medicinal plant combines with the metal ions of nanosize. The present chapter is focused on the bioactivity of nanoparticles synthesized from medicinal plants. The present chapter is definitely helpful in enriching the depth of knowledge among academician sand lay persons too.