In the design of actively controlled structures, the determination of the actuator locations is a very important issue. In order to find the optimal placements of piezoelectric acutators in adaptive truss structures, optimal placement strategies developed in conjunction with the independent modal space control method are used in this paper. For this purpose, a finite truss element is developed accounting for the piezoelectric actuators. By using this finite element, eigenvectors consisting not only of nodal displacements but also of electric potentials are computed. The optimization algorithm calculating the optimal actuator placements makes use of the electric potentials to minimize the control effort. The minimization of the spillover energy into uncontrolled modes is an additional objective which can be taken into account by the optimization procedure. The method is illustrated by numerical examples. © 1994 Academic Press Limited.