In this study, the antimicrobial activity of colloidal silver nanoparticles prepared by the sol-gel method was investigated, and the turbidity, viscosity and pH of the colloidal solutions were determined. The size of the silver nanoparticles was measured by Atomic Force Microscopy (AFM). The minimum inhibitory concentration (MIC) value of the colloidal solution resistance to test microorganisms Escherichia coli, Staphylococcus aureus, Candida albicans, Bacillus subtilis, Salmonella typhimurium, Pseudomonas aeruginosa and Klebsiella pneumoniae was carried out by the Broth Microdilution Method. It was found that the silver nanoparticles inhibited the growth and multiplication of the tested microorganisms, including the fungus C. albicans. The antimicrobial activity was observed against all tested microorganisms at a very low concentration of 2-4 mu g/ml of nano silver.