The forthcoming introduction of the DRG-system as a new hospital funding system in Germany reinforced the discussion about a reform of the already existing funding system in medical rehabilitation. Experience and concepts from acute medicine, however, cannot be transferred directly to rehabilitation. The development of a patient classification system is a presupposition for prospective payment systems. Initial attempts in rehabilitation-specific patient classification systems already exist, even though a comprehensive approach is not yet noticeable. International patient classification systems scarcely seem to be transferable due to the specific German case-mix. The specific differences between acute medicine and medical rehabilitation relevant for the valuation of funding systems are analyzed. Particularly a reduction of the length of stay as a primary aim for the introduction of the DRG-system does not seem appropriate for medical rehabilitation. The existing funding system in medical rehabilitation is analyzed from an economic point of view. The cost management of the German pension insurance, being one of the rehabilitation providers in Germany, has achieved high quality standard of treatment as well as cost restriction. This funding system has been further developed during the last couple of years. Future developments are shown.