: The paper describes an approach for run-time modifying and adaptation of a complex GUI using a rule-based system. Elements of Intelligent User Interfaces (IUI) paradigm, involved in this approach are discussed. A WEB-based solution, implementing the ideas, discussed in the article, is overviewed. The problems, technical solutions and the advantages of the selected approach are listed. Key words: Intelligent User Interfaces (IUI), Rule based systems, Clips, Real time GUI generation, Computer Systems and Technologies