Situations managed by clinical practice guidelines (CPGs) usually correspond to general descriptions of theoretical patients that suffer from only one disease in addition to the specific pathology CPGs focus on. The lack of decision support for complex multiple-disease patients is usually transferred to computerbased systems. Starting from the GEM-encoded instance of CPGs, we developed a module that automatically generated IFTHEN- WITH decision rules. A two-stage unification process has been implemented. All the rules whose IF part was in partial matching with a patient clinical profile were triggered. A synthesis of triggered rules has then been performed to eliminate redundancies and incoherences. All remaining, eventually contradictory, recommendations were displayed to physicians leaving them the responsibility of handling the controversy and thus the opportunity to control the therapeutic decision.