The main aim of every medical intervention is to improve the "quality of life" of the patients. In recent years, quality of life assessment has become increasingly important as an additional outcome measure in clinical research. The evaluation of quality of life is particularly relevant in patients with end-stage renal disease. The characteristics of the clinical condition in fact--no cure of the pathological state, and the type of the heavy non-stop treatment programs--obviously have an important impact on the patients' quality of life. Mortality, of course, is not an optimal or satisfactory outcome to assess the quality of care provided to these patients. After a general introduction of the current debate on methodological issues in quality of life evaluation, this paper reports several instruments described in the literature to evaluate the quality of life in patients with renal disease. Compared to other medical fields the number of questionnaires available for patients with renal disease is limited. The domains investigated are well defined in terms of generic concepts and disease-specific domains, principal symptoms, and the validity of the questionnaires is generally well documented.