Silver nanoparticles are known to have antimicrobial activity. In this study, we investigated the effect of silver nanoparticles on biofilms of different human pathogenic bacteria. Silver nanoparticles at concentrations of 25-50 ppm inhibited biofilm formation in all the five tested pathogenic bacteria. The particles also have potential as biofilm-removing agents, as shown by their ability to destroy Salmonella and Pseudomonas spp. biofilms.