Renal function in autologous hematopoietic cell support for breast cancer. Autologous and allogeneic bone marrow grafting both require cytoreductive therapy but only the allogeneic procedure requires immunosuppressive agents. Allogeneic bone marrow transplantation has been reported to be associated with a high incidence of both renal failure and veno-occlusive disease (VOD) of the liver, the combination of which is associated with a high morbidity and mortality. There is less known about the frequency and severity of these complications in patients undergoing autologous bone marrow transplantation. In the present study renal, hepatic and other complications were examined in 232 patients with Stages II/III and IV breast cancer who were treated with high-dose chemotherapy and autologous hematopoietic cell support with either marrow or peripheral blood progenitor cells. The post-treatment severity of the renal dysfunction was classified as follows: Grade 0, normal renal function [< 25% decrement in glomerular filtration rate (GFR)]; Grade 1, mild renal dysfunction (> 25% decrement in GFR but < a twofold increase in serum creatinine); Grade 2, > twofold rise in serum creatinine but no need for dialysis; Grade 3, > than twofold rise in serum creatinine and need for dialysis. There were 102 patients (44%) who were classified as Grade 0 and 81 patients (35%) who were classified as Grade 1 renal dysfunction. Severe renal dysfunction (Grades 2 and 3) was observed in 49 of the 232 patients (21%). This severe renal dysfunction of 21% compares with a previously reported 53% incidence of severe renal dysfunction for allogeneic bone marrow transplantation. Similarly, the frequency of hepatic VOD was less (4.7% or 11 of 232 patients) in this autologous bone marrow transplant study as compared to a reported incidence of hepatic VOD ranging from 22 to 53% in large series of allogeneic bone marrow transplant patients. The severe renal dysfunction (Grades 2 and 3) in the present autologous hematopoietic cell support study correlated most significantly with sepsis, liver and pulmonary dysfunction. The major fall in GFR occurred during chemotherapy but before hematopoietic cell support, thus primarily incriminating the cytoreductive therapy rather than the hematopoietic cell support. The only significant effect of different chemotherapy protocols was, at four weeks, the Taxol-treated group had a significantly lower creatinine clearance as compared to the BCNU treated group.