In the present study biosynthesis of silver nanoparticles (SNPs) by Berberis vulgaris and Ziziphus zizyphus fruit extracts was examined and antibacterial effect of the produced nanoparticles against some bacterial pathogenic strains was investigated. For this reason, the fruit aqueous and methanolic extracts of barberry and jujube were prepared and subjected to the silver nitrate solution at the final concentration of 1 mM. After nanoparticles production, all the color changed reaction mixtures were analyzed through visible spectrophotometer, X-ray diffraction analysis (XRD) and transition electron microscope (TEM). Finally the antibacterial effect of the produced nanoparticles was investigated by agar well diffusion method. Results showed that after nanoparticles production, the color of the plant extracts was converted to dark brown. Visible spectra of all the color changed extracts had maximum absorption peaks around 420-440 nm wavelength. Furthermore, presence of the SNPs was confirmed by XRD. TEM analysis revealed that the obtained SNPs were spherical in their shapes and their average sizes were around 5-50 nm. Antibacterial assays revealed that the produced nanoparticles in comparison with the control and the pure fruit extracts had more effective antibacterial activity. Moreover, statistical analysis has demonstrated that the antibacterial effects of these nanoparticles against all of the tested bacterial strains have showed similarity.