There is little information available regarding the outcome of unrelated bone marrow transplantation (BMT) for non-Hodgkin lymphoma (NHL). Therefore, we retrospectively analyzed the data of 124 patients who underwent unrelated BMT through the Japan Marrow Donor Program (JMDP) between July 1992 and August 2001. The overall survival (OS), progression-free survival (PFS), cumulative incidences of disease progression, and nonprogression mortality at 3 years after BMT were 49.7%, 42.6%, 24.5%, and 32.9%, respectively, with a median follow-up duration of 565 days among survivors. The incidence of grades II-IV acute graft-versus-host disease (GVHD) was 40.9%. Recipient age, previous history of autologous transplantation, and chemosensitivity at transplantation were independent prognostic factors for OS and PFS. The development of grades II-IV acute GVHD was associated with lower incidence of disease progression after transplantation, which suggested the existence of a graft versus lymphoma effect. Unrelated BMT should be considered as a treatment option for patients with high-risk NHL without an HLA-matched related donor.