The aim of present investigation was to synthesis the nanoparticles by using the medicinal plant Ocimum basillicum. Biologically synthesized nanoparticles have been widely used in the field of therapeutic medicine. The silver nanoparticles were synthesized by using 1mM aqueous of silver nitrate with leaf extract of Ocimum basillicum. The growth of nanoparticles is monitored by visualizing color changes and it was confirmed by the techniques, UV-vis spectrophotometer and characterized by Scanning Electron Microscope (SEM), Fourier Transform Infrared Spectroscopy (FTIR) and X- ray diffraction (XRD) analysis. The result of varies techniques confirmed the presence of silver nanoparicles and showed the average particle size between 58-89nm. Further the synthesized nanoparticles are evaluated for its antimicrobial activity against on selected bacterial species.