Strategic market management (SMM) is the process of establishing a sustainable competitive advantage. Essential cause-effect relationships in SMM are mostly logical, the problem-solving semi- or unstructured, and available knowledge mostly imprecise and incomplete. Recent studies have shown that expert systems show significant promise for improving the basis and conceptual framework for decision-making in a strategic market management context. Expert systems are designed to capture problem-solving and decision-making processes which are carried out by an expert well versed in both the theory and practice of the problem contest. The development of a rule-based expert system is described and it is shown how it can be used as an SMM support system