The use of at least one modified polysaccharide selected from starch, amylose, amylopectin and dextrin or a mixture thereof substituted with one or more amine and/or ammonium groups, as an antimicrobial agent, is provided by the present invention, as well as compositions comprising a polymer material blended with the modified polysaccharide. Also provided by the present invention are antimicrobial articles produced from the compositions of the invention and antimicrobial surface, fabric, foam or sponge produced by coating, soaking or dipping in a solution comprising modified polysaccharides. The present invention further provides non-therapeutic methods for killing microorganisms, inhibiting their growth, and/or preventing formation of a biofilm, and for producing an antimicrobial surface, article, fabric, foam or sponge from modified polysaccharides.