E-mail: chc12@chonnam.ac.kr (H. C. Choi); cwlee@jnu.ac.kr (C. W. Lee)Received July 4, 2013, Accepted August 9, 2013Carbon nanocomposites composed of carbon nanostructures and metal nanoparticles have become one ofuseful materials for various applications. Here we present the preparation and antibacterial activity of CNT-Agand GO-Ag nanocomposites. Their physical properties were characterized by TEM, XPS, and Ramanmeasurements, revealing that size-similar and quasi-spherical Ag nanoparticles were anchored to the surfaceof the CNT and GO. The antibacterial activities of CNT-Ag and GO-Ag were investigated using the growthcurve method and minimal inhibitory concentrations against Gram-negative and Gram-positive bacteria. Theantibacterial activities of the carbon nanocomposites were slightly different against Gram-positive and Gram-negative bacteria. The proposed mechanism was discussed.Key Words : Carbon nanostructures, Ag nanoparticles, Antibacterial activity, Gram-negative, Gram-positiveIntroductionAntibiotic resistance is a serious and growing phen-omenon in public health and a big task in the field ofpharmaceutical and medicine. Resistant pathogenic strainsare emerging at a rate that far exceeds the speed of newantibiotic development. Therefore, the novel class of anti-biotics having different mechanism of action in comparisonto existing antibiotics is urgently needed. In the research areaof antibiotics, development or searching of the antimicrobialcompounds having improved or distinct antibacterial activityagainst multidrug-resistant (MDR) human pathogenic micro-bes is a primary intention.