Colloidal solutions of Titanium dioxide nanoparticles were synthesized by laser ablation of Titanium plate in deionized water. Studies of synthesized nanoparticles suspensions were characterized by UV-VIS absorption, Fourier transform infrared spectroscopy (FTIR) and transmission electron microscope (TEM). FTIR characterization confirms the formation of Titanium dioxide nanoparticles. TEM shows that the nanoparticles with sizes from (3 - 30) nm. The antimicrobial activity was carried out against Staphylococcus aureus and Escherichia coli. The Titanium dioxide nanoparticles showed inhibitory activity in bacteria.