Introduction Hematopoietic stem cell transplantation (HSCT) aims to cure multiple hematologic malignancies, nonmalignant diseases, metabolic disorders, and immune deficiencies. Along with other transplant-related organ toxicities, both acute and chronic kidney disease are common complications of allogeneic HSCT, affecting 10% to 73% and 0% to 60% of patients respectively, depending on the definitions of kidney dysfunction, duration of follow-up and transplant strategies.S1–S4 The proportion of patients with chronic kidney disease who develop end-stage renal disease is approximately 4%. Among those patients who progress to end-stage renal disease and require hemodialysis, mortality is approximately 90%. Few studies have reported successful kidney transplantation (KT) after HSCT in adults; these were mostly small single-center cohorts often with the same donor for HSCT and kidney, and short follow-up.1 ,2 To investigate mortality and the occurrence of severe infections and cancers, we conducted a French multicenter retrospective study of patients who underwent KT, after previous allogeneic HSCT. The details of study methods are shown in the Supplementary Methods. Results Nineteen KT patients with a history of HSCT were identified, of whom 3 had received a kidney from the HSCT donor: the remaining 16 patients were included in the analysis (Table 1 and Supplementary Table S1). Patients were allografted between 1986 and 2006, including 12 patients before 2000, at a median age of 31 (9–55) years (3 pediatric patients and 1 patient older than 45 years). The main indication for HSCT was acute leukemia (n = 11/16: 8 acute myeloid leukemia and 3 acute lymphoblastic leukemia). Three patients had undergone 2 consecutive HSCT (2 relapses and 1 autologous HSCT before allogeneic HSCT). Myeloablative conditioning (n = 14/16) was performed and the graft came from a matched related donor (n = 12/16) in the majority of cases. Baseline nephrologic status was partially or fully available for 9 patients. At the time of HSCT, the 2 most recently allografted patients, the only ones to receive nonmyeloablative conditioning regimen, were already on hemodialysis. Two patients were with stage 2 chronic kidney disease and 5 had no kidney failure.