Developing of new antibiotics with synergistic properties is of great importance. Herein, the synthesis of cephalexin nanoparticles (CPNPs) is reported through ball milling method for the first time. Cephalexin powders had an initial size in the range of 10-100 mu m. The average particle size, however, was reduced to about 100 nm after milling for 7 h, confirmed by SEM. Silver nanoparticles (AgNPs) with small particle size (<10 nm) were synthesized through chemical reduction of silver ions in citrate solution. The cytotoxicity of the prepared CPNPs and AgNPs at different concentrations were evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MIT) reduction assay. The antibacterial properties of CPNPs, AgNPs and their combination were investigated against Staphylococcus aureus. The results confirmed that AgNPs show synergistic properties in the presence of CPNPs and effectively increased their antibacterial properties. (C) 2017 Elsevier B.V. All rights reserved.