Magnetorheological dampers are playing an increasingly important role in many areas of vibration control. This increased role stems from better understanding of the properties of rheological fluids, more sophisticated methods of damper manufacture, improved magnetorheological (MR) damper characterisation, and the use of advanced control strategies. An important feature of MR dampers is their potentially-broad suppression frequency range, from low-frequency seismic response in building structures to vibro-acoustic frequencies in aircraft panels.