Chitosan as a natural polymer has been converted into nanofibers and the effect of silver nanoparticle on the antibacterial properties of the nanocomposite fibers has been investigated. Chitosan (Cs)/poly(vinyl alcohol) (PVA) solutions in 2% (v/v) aqueous acetic acid were electrospun. The effects of different total concentrations of polymer solution and mass ratios of Cs and PVA on the fibers formation and its morphology have been investigated by SEM. Effect of spinning parameters on the nanofiber diameter have been investigated. Fine nanofibers, without bead were obtained in 8% total concentration of polymer in aqueous acetic acid solution and 40/60 mass ratio of Cs/PVA. . To improve the antibacterial properties of nanofibers silver was incorporated in to the electrospinning solution by two different ways. . First silver nanoparticles were added into the electrospinning solution. and addition of silver nitrate salt and then reduct it to silver. Evaluation results of antibacterial activity of nanofibers against St.aureus as gram-positive and P.aeruginosa as gram-negative bacteria, shows that nanofibers containing silver nanoparticles have stronger antibacterial activity than nanofibers without silver. Moreover; cell culture test shows that these nanofibrous webs are able to grow cells and can be use as scaffold in tissue engineering applications.