As chronic diseases are continuously increasing in our aging society, the description and improvement of quality of medical care needs critical examination of the multidimensional subject of "quality of life". Health-related quality of life is currently used as an outcome-criterion in modern medicine. As there is no generally accepted definition of quality of life, various components of the state of health and the patient's behaviour are recorded by questionnaires. The level of subjective well- being is determined by several dimensions such as physical constitution of the patient, state of mind, functional competency in everyday life and the form of interpersonal relationships. Based on these principles various instruments for measuring quality of life are developed. The assessment of the subjective quality of life reflects the increased acceptance of the patient's view. In addition to the common generic instruments such as SF-36, FLZ(M), MLDL, EQ-5D, WHOQOL-100, NHP, SIP, also disease-specific instruments e.g. for peripheral arterial disease are currently used (PAVK-86, CLAU-S, VASCUQOL, SIP(IC), and WIQ). At the moment SF-36 is the best established questionnaire as generic QOL instrument. FLZ(M) takes the individual weighting of items into account, by correlating the importance and the contentment for life. For evaluating the effectivity of medical outcome and the success of therapeutic treatment for patients with vascular disease, the VASCUQOL instrument seems to be the best choice. Simultaneous application of a generic instrument and disease-specific questionnaires displays as well the subjective quality of health as the individual impairment of the patient in a good way. As a consequence using both instruments is superior to the exclusive use of a generic questionnaire.