This paper provides a design method of fixed-structure robust controllers satisfying multiple H. norm specifications by using a sort of randomized algorithms. First, a new tool to perform general constrained optimization is developed which does not need any gradient or derivative of the objective function. This tool is based on a particle swarm optimization (PSO), which has attracted a lot of attention recently in the evolutionary computation area due to the empirical evidence of its superiority in solving various non-convex problems. Second, it is shown how to design a fixed-structure controller satisfying given multiple H. specifications by using the developed optimization tool. Third, its effectiveness is evaluated through various numerical examples, because it is difficult to guarantee the performance of the proposed method theoretically due to the probabilistic nature of PSO. The simulation results demonstrate its effectiveness clearly. (C) 2008 Elsevier Ltd. All rights reserved.