Silver nanoparticles (AgNPs) have emerged as an important class of nanomaterials for a wide range of industrial and medical applications. However, the unique properties of AgNPs could potentially lead to unexpected hazards to both human health and the well being of the environment. Possible mechanisms of AgNP-induced toxicity include the stimulation of oxidative stress, genotoxicity and apoptosis. In this study, a number of previous studies are therefore summarized that demonstrate oxidative stress-, genotoxicity- and apoptosis-related changes brought about by AgNPs in cultured cells and animal tissues. The physicochemical properties of AgNPs that are involved in encouraging such changes are also discussed. Copyright © 2012 John Wiley & Sons, Ltd.