We examined whether the use of G-CSF-primed unmanipulated bone marrow (pBM) permits successful transplantation in patients with adverse comorbid pretransplantation conditions. A total of 33 patients at variable risk of AML undergoing allogeneic SCT from an HLA-identical sibling participated. The patients suffered from a variety of treatment-related sequelae before SCT and many cases also featured the presence of major organ dysfunction. The median follow-up duration of patients who were among the overall survivors was 58 months (range, 11-125 months). The median number of CD34(+) cells infused was 3.5 x 10(6) per kg (range, 0.8-15.6 x 10(6) per kg). The median number of days for recovery of ANC and platelet count without transfusion was 13 (range, 6-22) and 18 (range, 11-29) days, respectively. Four patients (12%) died due to nonrelapse causes and only one patient developed the same course of infectious complication as before SCT. No particular finding in the context of CMV infection or other post transplant complication was observed. The estimated 10-year overall survival rate was 68%. Our results suggest that the use of pBM allows successful engraftment without increasing complications in patients with various comorbidities before transplantation.