The concept of quality of life (QL) is hardly discussed with respect to quality management in patient care. We will show that QL-assessment can make important contributions to quality management. QL is assessed by means of standardized questionnaires and can be displayed in the form of quality of life profiles. These results are important since patients self-assessments often differ to a large extent from physicians' judgements. QL-profiles allow for a depiction of the individual case at a given time, as well as for the evaluation of the course of therapies. Adopting this methodological concept, a large field study involving practitioners in the region aims at researching therapy outcomes with regard to rectal and breast carcinoma. Regular interim data analyses and discussion of the results in quality circle groups focuses at the immediate eliminating of mismanagement in patient care (action research).