A longitudinal study of 979 patients with end-stage renal disease from 27 dialysis centers in the Upper Midwest was conducted to measure the patients' functional status with use of the Karnofsky Activity Scale. At the initiation of dialysis, 50% of all patients were rehabilitated or caring for themselves, and the three variables that most influenced the initial rehabilitation score were age, diabetic status, and sex. Initial functional status was also analyzed for three cohorts of dialysis patients, grouped according to outcome (renal transplantation, continued dialysis, and death). Patients who received a renal transplant had initial rehabilitation scores that were higher than those who underwent dialysis for 2 years or those who died. In the group of patients who underwent dialysis for 2 years, a statistically significant improvement in rehabilitation scores was noted at 2 years in comparison with the scores obtained at the initiation of dialysis. Initial rehabilitation scores were good predictors of the 2-year scores. Of the patients in the 2-year dialysis cohort, 78% maintained or had improvement in their functional status.