Abstract. Evolutionary methods are now beginning to be used routinely in design applications. However, even with computing speeds growing continuously, for many complex design problems evolutionary computing times are so long that their use is not practical. Divide and conquer based methods sometimes improve the situation, but in most cases the biggest speed improvement can be gained by adding domain knowledge. Combining evolutionary methods with conventional design methods is one way of doing this. This paper shows how evolutionary computation can be used to improve designs created by conventional design methods. A digital filter design problem is used to illustrate how a conventionally derived design can be further improved by evolutionary calibration. Our experimental results show that the evolutionary calibration algorithm is able to consistently improve the original designs by a considerable margin.1