Synthesis of silver nanoparticles by biological route represents as economic alternative for physical and chemical methods of nanoparticles formation. Biosynthesis of silver nanoparticles using bottle gourd (Cucurbita lagenaria L.) fruit extract was investigated. Silver nanoparticles were characterized using UV-Vis absorption spectroscopy, absorption peak was obtained at 435 nm. X-Ray diffraction and Scanning Electron Microscopy analysis showed that silver nanoparticles were spherical with average particles size of 27.4 nm. These were found to be toxic against Klebsiella pneumoniae NCIM 2719 and Clostridium acetobutilicum bacteria