Features of expert systems applied in manufacturing design are presented. Three issues in expert systems, namely, knowledge repre sentation, knowledge acquisition, and inference strategy, are briefly dis cussed. The tandem architecture of expert systems that allows for close interaction of the inference engine with a set of models and algorithms is outlined. Four design problems in manufacturing systems, namely, part design, process planning, equipment selection, and facility layout, are identified. Existing expert systems developed for the design problems are surveyed.