Stimuli-responsive membranes change their physicochemical properties in response to changes in their environment. Stimuli-responsive membranes have been designed to respond to changes in pH, temperature, ionic strength, light, electric and magnetic fields, and chemical cues. This review covers the design of stimuli-responsive membranes and their ever-expanding range of use. It considers stimuli-responsive changes in membrane structure and surface characteristics that enable novel applications. (C) 2010 Elsevier B.V. All rights reserved.