Minimal residual disease (MRD) is associated with adverse outcome in acute myeloid leukemia (AML) after myeloablative (MA) hematopoietic cell transplantation (HCT). We compared this association with that seen after nonmyeloablative (NMA) conditioning in 241 adults receiving NMA (n= 86) or MA (n= 155) HCT for AML in first remission with pre-HCT bone marrow aspirates assessed by flow cytometry. NMA patients were older and had more comorbidities and secondary leukemias. Three-year relapse estimates were 28% and 57% for MRD neg and MRD pos NMA patients, and 22% and 63% for MA patients. Three-year overall survival (OS) estimates were 48% and 41% for MRD neg and MRD pos NMA patients and 76% and 25% for MA patients. This similar OS after NMA conditioning was largely accounted for by higher non-relapse mortality (NRM) in MRD neg (30%) compared with MRD pos (10%) patients, whereas the reverse was found for MRD neg (7%) and MRD pos (23%) MA patients. A statistically significant difference between MA and NMA patients in the association of MRD with OS (P< 0.001) and NRM (P= 0.002) but not relapse (P= 0.17) was confirmed. After adjustment, the risk of relapse was 4.51 times (P< 0.001) higher for MRD pos patients. These data indicate that the negative impact of MRD on relapse risk is similar after NMA and MA conditioning.