show very high activity against Gram-positive and Gram-negative bacteria including clinical isolated strains e.g. highly multiresistant strains such as S. epidermidis, S. aureus and Pseudomonas aeruginosa. Since such results indicated that use of silver nanoparticles can be pursued as an alternative strategy (to antibiotics)for reducing bacterial adhesion and to prevent bacterial bio-film formation, we decided to perform similar tests for copper nanoparticles as potential new antimicrobial agents and compare their activity against some standard and clinical gram-positive bacteria strains. The obtained results of antibacterial tests (MIC) for copper nanoparticles are summarized in Tables 1 and 2.