In the present study, the biosynthesis of TiO 2 nanoparticles (TiO 2 NPs) was achieved by a novel, biodegradable and convenient procedure using Aspergillus flavus as a reducing and capping agent. Research on new, simple, rapid, eco-friendly and cheaper methods has been initiated. TiO 2 NPs were characterized by FTIR, XRD, AFM, SEM and TEM studies. The X-ray diffraction showed the presence of increased amount of TiO 2 NPs which can state by the presence of peaks at rutile peaks at 1 0 0, 0 0 2, 1 0 0 and anatase forms at 1 0 1 respectively. SEM observations revealed that synthesized TiO 2 NPs were spherical, oval in shape; individual nanoparticles as well as a few aggregate having the size of 62-74 nm. AFM shows crystallization temperature was seen on the roughness of the surface of TiO 2. The Minimum inhibitory concentration value for the synthesized TiO 2 NPs was found to be 40 μg ml -1 for Escherichia coli, which was corresponding to the value of well diffusion test. This is the first report on antimicrobial activity of fungus-mediated synthesized TiO 2 NPs, which was proved to be a good novel antibacterial material. © 2012 Elsevier B.V. All rights reserved.