The indication of allogeneic stem cell transplantation (allo-SCT) for Philadelphia chromosome-negative acute lymphocytic leukemia [Ph(-) ALL] from unrelated donors is not established. To assess its potency of unrelated patients in first complete-remission (CR1) transplanted from unrelated donors and the potential prognostic factors affecting the probability of survival, we retrospectively analyzed a total of 41 adult Ph(-) ALL patients in CR1 who underwent unrelated bone marrow transplantation at 6 transplantation centers of the Nagoya Blood and Marrow Transplantation Group between 1993 and 2006. The median age of the 41 patients was 28 years (range, 18-51 years). HLA was matched in 33 transplants, with mismatches in 8 (HLA-A allele mismatch:1, HLA-DR serological mismatch: 2, HLA-DRB1 mismatch: 5). Leukemia-free survival (LFS) at 3 and 6 years from allo-SCT was 60.3 and 47.7%, respectively. LFS at 5 years was 62.1% for those transplanted from HLA-matched donors. LFS was significantly lower with HLA-mismatched donors due to higher transplantation-related mortality. Relapse was observed in 3 patients. Our study suggested that unrelated allo-SCT could improve LFS of patients with a potential graft-versus-leukemia effect. Unrelated allo-SCT for Ph(-) ALL patients in CR1 could be more beneficial by reducing TRM, such as selecting a HLA-matched donor.