A　controllability　assessment　of　plate-like　structures　with　uncertainties　under　piezoelectric　actuation　is　performed　in　this　paper.　Different　from　the　previous　studies,　a　novel　index　is　proposed　to　quantify　the　degree　of　controllability　using　the　sensor/actuator　transfer　function.　Influences　of　unmodelled　high-frequency　dynamics　and　structural　parameter　variations　on　controllability　are　discussed,　and　the　relationship　between　the　indices　for　the　nominal　and　uncertain　cases　is　derived.　In　order　to　validate　the　controllability　assessment　numerically,　the　modelling　of　a　plate　with　piezoelectric　actuation　is　developed　with　the　consideration　of　the　full　coupling　between　the　PZT　actuators　and　the　host　plate,　and　verified　by　experiments.　It　is　demonstrated　that　a　proper　design　of　the　polyvinylidene　flouride　sensor　would　help　eliminate　effects　of　higher　order　modes　on　the　basis　of　strain　mode　shapes.　Since　the　latter　is　very　sensitive　to　the　mass　and　stiffness　added　by　PZT　actuators,　the　dynamics　of　PZT　actuators　must　be　taken　into　account　during　the　design,　as　opposed　to　the　case　where　a　point　transducer　is　used.　©　2003　Elsevier　Ltd.　All　rights　reserved.