The definition of rehabilitation for end-stage renal disease (ESRD) patients has changed significantly over the past 40 years. Initially, the concept focused on return to employment. In the early days, most members of the small select group of patients chosen for dialysis met this criterion and were considered successfully rehabilitated. However, this "success" could not be replicated in the broader ESRD population when Medicare coverage was expanded to include older and more debilitated patients. This raised serious questions about the feasibility of renal rehabilitation efforts. Government policy makers and the nephrology community responded by (1) gathering data to enable the measurement and improvement of health-related quality of care, and (2) redefining rehabilitation and its goals. Today, renal rehabilitation is defined broadly, in terms of optimal functioning for individual patients and restoration to productive activities-not simply employment. To foster renal rehabilitation and guide program development, the Life Options Rehabilitation Advisory Council (LORAC) identified five core principles, called the "5 E's"-Encouragement, Education, Exercise, Employment, and Evaluation. Considerable progress has been made in measuring outcomes of care and in establishing a connection between rehabilitation interventions and improved outcomes. Increasingly, research is focused on the relationship between patient self-reports and health status outcomes. In the years ahead, clinicians and researchers will see growing evidence of relationships between specific rehabilitation interventions, improved outcomes (including health-related quality of life), and cost-effective delivery of care. (C) 2000 by the National Kidney Foundation, Inc.