A green, low-cost and reproducible Eclipta leaves negotiated synthesis of silver nanoparticles is reported. The synthesis is performed at room temperature. X-ray and transmission electron microscopy analyses are performed to ascertain the formation of Ag nanoparticles. Nanoparticles almost spherical in shape having a size of 2-6 nm are found. UV-visible study revealed the surface plasmon resonance at 419 nm. The lattice strain is estimated to be 0.0045 using Williamson-Hall approach. The use of Eclipta for the synthesis of silver nanoparticles offers the benefit of ecofriendliness and amenability for large scale production through scaling up. (C) 2009 American Institute of Chemical Engineers Biotechnol. Prog., 25: 1476-1479, 2009