Nanoparticle based agents often applied as coatings on biomaterials have shown promise in delivering the improved sterility against variety of microbes. In the present study, silk fibers (SF) were coated with chitosan impregnated with silver nanoparticles (Ag-C-SF). These Ag-C-SF fibers were characterized using scanning electron microscopy (SEM) with energy dispersive X-ray analysis, atomic force microscopy (AFM), Infra Red spectroscopy, Thermogravimetric Analysis and Microbiological assay techniques. AFM studies have confirmed the nano sized silver particles in chitosan solution; SEM pictures have exhibited the coating of chitosan along with silver nanoparticles on the silk fibroin. The modified fibers have also shown anti-microbial activity and improved thermal stability. The Ag-C-SF fibers may be explored as wound dressing and tendon reconstruction material in future. © 2011 Springer Science+Business Media, LLC.