The healthcare sector is currently facing both the economic necessity and the technical opportunity of a data based approach to quality management. Against this background, a process model for such a data based medical quality management is proposed and intelligent data mining methods are applied to patient data. Intelligent data mining incorporates advantages of both knowledge acquisition from data and from experts. A controlled language for business questions is presented which abstracts from database and data mining terminology to allow high-level interaction. Objective and subjective interestingness of results is measured and used to filter and sort.