Objective - To assess the quality of life (QOL) of patients with end-stage chronic kidney disease (on dialysis or who have undergone a transplant) and to identify associated factors. Methods - Two cross-sectional studies were conducted in 2005 and 2007 among patients over 18 years of age who were being followed in one of the eight regions of the Nephrology Epidemiology and Information Network (Rein) in 2005, specifically dialysis patients and transplant recipients, respectively. Patients were randomly selected after stratification by age and region. QOL was measured using the MOS-SF36 and a specific questionnaire—the KDQOL (Kidney Disease Quality of Life) for dialysis patients and the ReTransQol for transplant recipients—and compared to that of the general population.Results - 832 dialysis patients and 1,061 transplant recipients were included, with response rates of 67.1% and 72.5%, respectively. QOL scores were higher (by 10 to 30.6 points) among transplant recipients than among dialysis patients across all dimensions of the SF-36. The main associated factors were sex, age, duration of dialysis, and the presence of comorbidities. Among transplant recipients, treatment side effects had a marked detrimental effect. Conclusion - Differences in quality of life between dialysis patients and transplant recipients compared to the general population highlight the benefits of kidney transplantation. The associated factors suggest avenues for improvement. (R.A.)