This paper studies a design problem concerning installation locations for a number of structural magneto-rheological (MR) dampers. The mechanical characteristic of each MR damper is functional dependent to an input current, which is regulated by a Fuzzy Logic controller. It is demanded that the chosen arrangement of dampers should change the dynamic response of the structure to meet certain constraints expressed in terms of minimization of an objective function. For this purpose, an improved version of Ant Colony Optimization algorithm is presented. The modified algorithm also utilizes additional heuristic data derivable from a pre-analysis of the structure in the optimization procedure. Further improvements regarding convergence speed of search algorithm are proposed as well, provided numerical examples study the functionality of the algorithm in different cases. With an acceptable probability from a structural designer's point of view, the proposed method finds qualified solutions during a reasonable number of search iterations. Copyright © 2011 John Wiley & Sons, Ltd.