An experimental knowledge-based menu design assistant (MENUDA) was developed to aid the design of menu systems. A conceptual model was first developed to provide a structured construct to organize knowledge of menu system design from the available literature, and to serve as a paradigm for the development of the MENUDA system. The knowledge base and the user interface of the MENUDA system were developed under an interactive microcomputer environment supported by Texas Instruments' Personal Consultant Plus. The current version of the MENUDA system is described in the paper. In addition, the methodology used to derive rules in the MENUDA knowledge base and the appropriateness of employing a knowledge-based expert system approach to providing user interface design guidelines are discussed.