Nanotechnology is an emerging interdisciplinary subject that has been booming in many areas during the recent decade. Looking to this aspect, we synthesized undoped and Mn doped ZnO nanoparticles by chemical method using microwave irradiation for 20 sec at 720 watt. Energy dispersive analysis of X-rays (EDAX) confirmed that the synthesized nanoparticles do not contain any foreign elements in them. The particle size, shape and morphology were examined by Transmission electron microscopy (TEM). The potential toxicity of nanosized ZnO and Mn doped ZnO were investigated using Staphylococcus aureus, Escherichia coli, Bacillus subtilis, Pseudomonas aeruginosa, Serratia marceseus and Proteus vulgaris bacteria as test organism. The result showed that nanoparticles dispersed in methanol medium enhanced the antibacterial activity.
