The emergence of expert systems provides new insights for the design of a computerised system for selecting cam-follower design parameters. CAMEX is an expert system for industrial cam-follower mechanism design. Cam-Follower design is similar to most applications for expert systems in design and manufacturing in the sense that it involves not only a wealth of work knowledge but also intensive computation. In other words, the parameter selection process involves much symbolic and numerical computation. How to organise the heuristic rules and design algorithms so as to generate optimum design parameters efficiently is a big challenge. In this paper, the theoretical foundation of CAMEX, an expert system which generates optimum cam-follower design parameters, is discussed. The functional structure and operational procedure of the system are examined in detail.