Quality of life (QoL) assessment is becoming increasingly important for measuring the impact of illnesses, diseases, and their treatment and for deciding priorities when allocating resources. We developed a novel method to measure QoL from the perspective of the individual patient. The schedule for the evaluation of individual quality of life (SEIQoL) was devised from the technique known as judgment analysis to measure patients' level of functioning in five self-nominated facets of life and the relative weight or importance attached to these areas. We applied this method, together with traditional measures of health status, in a prospective intervention study of 20 patients undergoing unilateral total hip-replacement surgery with six-month follow-up by comparison with matched, non-patient controls. Health status was significantly improved by hip replacement on the McMaster health index questionnaire (p less than 0.001) and the arthritis impact measurement scales (p less than 0.001). Individually measured QoL was significantly increased after surgery when measured by SEIQoL (p less than 0.02). The individual nature of QoL was reflected in the variety of life areas nominated as important by individual patients, the differences in relative weights attached to these areas, and the complex nature of the changes that occurred postoperatively. Our data not only highlight such individuality but also show that SEIQoL provides a means by which this can be assessed scientifically.