In large hospitals, huge amounts of data are generated by patient services. These mountains of data are often too large to manage. This thesis deals with the development of a patient data evaluation application in the context of a hospital reorganisation. An analysis of data structures was carried out and on the basis of this, the software architecture was built. Using flexible and customer-oriented software development, an analysis tool for the Inselspital Bern and the University Hospital Basel was created. With this tool it is possible to extract all the reasons for visits and room use and to analyse these in relation to cost centres and clinic budgets.