Advances in medical treatment have improved the rehabilitation potential of predialysis (P) and dialysis (D) patients, but deficits remain in their physical and vocational functioning. We studied 18 P (expected to begin dialysis in 6-12 months) and 18 D patients (on dialysis 1-5 years) for 1 year. Exercise coaching and rehabilitation counseling were provided at no cost for the first 6 months to half of each patient group (rehabilitation group = R); the other half were assigned randomly to controls (C). No R services were provided during 6 months of follow-up. PR walked further in 6 min at 6 months (+3.9 m) and 12 months (+4.1 m) than initially (p < 0.01). Hematocrit increased in R (p < 0.05), but not in C. Symptom scores were stable in D, worsened 21% in PC, and improved 15% in PR. Sickness impact profile scores were better in PR than PC at 6 months (p < 0.05) and 12 months (NS). Comorbidity correlated with symptoms (r = +0.34, p < 0.05), self-rated affect (r = -0.35, p < 0.05), and self-rated Karnofsky index of disability (r = -0.37, p < 0.05), but not with physician-rated affect or physician-rated Karnofsky index of disability. Thus, quality of life was stable or improved in PR, but declined in PC; PR benefited more than DR. Rehabilitation services are more beneficial before than after patients stabilize on dialysis, and quality of life monitoring should continue indefinitely.