Two commercially available alginate impression materials were incorporated with varying concentrations of zinc oxide nanoparticles (ZnO-NP) or copper oxide nanoparticles (CuO-NP) and their properties such as antimicrobial activity, gel strength,permanent deformation, gelation time and flow were measured. The results showed that alginates incorporated with nanoparticles exhibited concentration dependent antimicrobial activity. It was also observed that incorporation of nanoparticles did not adversely affect the clinically important properties of alginates. From these results, it can be concluded that incorporation nanoparticles to alginate materials can be considered for effective disinfection without significantly affecting their properties.