Summary:The aim of this study was to investigate the effect of a bone marrow transplantation (BMT) on renal function in children. In a 5-year period, 142 children received a BMT at the Department of Pediatrics of the University Hospital Leiden. The study was performed retrospectively using the estimated glomerular filtration rate before and 1 year after BMT, and weekly measurements of serum creatinine during the first 3 months after BMT for assessment of renal function. Patient characteristics (sex, age, diagnosis), conditioning regimen, type of BMT, major complications (sepsis, veno-occlusive disease and graft-versus-host disease (GVHD)) and the use of nephrotoxic medication were listed. In the first 3 months after BMT 17 (12%) patients died, 13 from transplant-related complications other than renal failure and four from relapse of the disease. Forty-eight children (34%) had a period with acute renal insufficiency. A high pre-BMT serum creatinine, transplantation with either a non-HLA-identical related or a matched unrelated donor were risk factors for acute renal insufficiency after BMT. Sepsis and the use of intravenous vancomycin were risk factors for acute renal insufficiency only for patients with a high pre-BMT serum creatinine. GVHD seemed to have a beneficial effect on renal function of BMT recipients. One year after BMT a total of 35 (25%) patients had died, 16 from transplant-related complications and 19 from relapse of the disease; another 17 patients could not be evaluated. Twenty-five of 90 evaluable children (28%) had chronic renal insufficiency. Chronic renal insufficiency 1 year after BMT was correlated with a high serum creatinine in the first 3 months after BMT. None of the children of this retrospective study on renal function after BMT needed dialysis. Keywords: bone marrow transplantation; child; renal insufficiency BMT has proven to be a good therapeutic approach for a wide range of hematologic, neoplastic, immunologic and Correspondence: Dr JE Kist-van Holthe, Department of Pediatrics, University Hospital Leiden, Postbus 9600, 2300 RC Leiden, The Netherlands Received 12 January 1998; accepted 7 May 1998 metabolic diseases. In the first 3 months post-BMT the transplant-related mortality rate approximates 10-20% in children. 1,2 The 5-year survival rate, dependent on the disease for which the bone marrow transplantation has been performed, varies from 90% for immunodeficiencies to 25% for hematologic malignancies in third remission. 1 The main steps of BMT are conditioning with intensive chemoradiotherapy to obtain engraftment of donor stem cells in the recipient, and prolonged immunosuppression to prevent GVHD. Major complications are (opportunistic) infections, GVHD and recurrence of primary disease. A major posttransplant complication that may contribute to transplantrelated mortality is acute renal insufficiency. 3,4 As BMT is the only curative therapy for some diseases, assessment of late complications becomes increasingly important. Understanding of the possible risk factors and the p...