Increasing medical complexity, centrifugal forces of medical subspecialization and growing economic constraints are the key reasons for the introduction of quality management into routine care processes such as dialysis. Adequate quality assurance and improvement must be implemented in order to supply medical staff, care providers, and patients with the necessary information on critical issues of clinical management of dialysis patients. QiN (Quality in Nephrology), the quality management program of the largest German dialysis provider, is outlined here as a practicable example. The first of 2 parts provides information on the structure, implementation of QiN and achieved clinical improvement in routine care. The second part (quotation) analyzes longitudinal data in order to differentiate whether observed improvements during more than 5 years of QiN can be ascribed to the intervention (application of QiN) or whether they are due to other factors such as generally improved medical knowledge.