Silver nanoparticles were successfully synthesized from AgNO3 through a simple green route using the latex of Jatropha curcas as reducing as well as capping agent. Nanoparticles were characterized with the help of HRTEM, X-ray diffraction and UV-vis absorption spectroscopy. X-ray diffraction analysis showed that the nanoparticles were of face centered cubic structure. A comparison of radius of nanoparticles obtained from HRTEM image with the optimized cavity radius of the cyclic peptides present within the latex revealed that the particles having radius 10-20 nm are mostly stabilized by the cyclic peptides. (C) 2009 Elsevier B.V. All rights reserved.