Background Obesity has been linked to poor access to medical care. Although scientific evidence suggest that kidney transplantation improves survival and quality of life in obese patients with end-stage renal disease (ESRD), few data exist on the impact of obesity on access to kidney transplantation in this population. Objectives We aimed to characterize the relationships between body mass index (BMI) at the start of dialysis, changes in BMI after the start of dialysis, and either access to kidney transplantation or overall mortality in dialysis or transplantation among ESRD patients. Methods Between 2002 and 2011, 19524 dialysis patients with ESRD were included in the study via the French nationwide Renal Epidemiology and Information Network. Data on sociodemographic factors, comorbidities and laboratory test results were recorded upon entry into the registry. BMI were obtained at the start of dialysis and then yearly. Cubic spline regression analyses provided a graphic evaluation of the relationships between BMI at the start of dialysis and outcomes. Joint models were used to evaluate the association between the change over time in BMI and outcomes. Results During a median follow-up of 20.3 months, 6634 patients underwent kidney transplantation. A BMI >31 kg/m(2) at the start of the dialysis was associated with a lower likelihood of receiving a kidney transplant, and the likelihood decreased even further with higher BMI values. For patients with BMI >= 30kg/m(2) at the start of the dialysis, a 1 kg/m(2) decrease in BMI during follow-up was associated with a 9% to 11% increase in the likelihood of receiving a transplant. There was an L-shaped relationship between BMI at the start of dialysis and overall mortality. We showed that obese patients with ESRD face barriers to the receipt of a kidney transplant without valid reasons. Conclusion Greater attention to this issue would improve the fairness of the organ allocation process and might improve outcomes for obese patients with ESRD.