50 patients with a median age of 41 years (range 29-54) underwent allogenic bone marrow transplantation for multiple myeloma. 35 patients were on second-line treatment, and 15 on first-line treatment. 24 patients were considered refractory to previous treatment. 45 patients received marrow from HLA-matched sibling donors (3 of these from twin donors), and 5 from unrelated or related non-sibling donors. 21 patients entered complete remission, while 15 had persistent disease following repopulation of the marrow. 14 patients were not evaluable for remission status because of early transplantation-related death. The overall median survival from bone marrow transplantation was 27 months, with a projected long-term survival of 34%. Patients who were 40 yr of age or older had a survival that was not different from that of patients between 29 and 40 yr of age. The median disease-free survival of patients who entered complete remissions was 41 months. These patients tended to have a longer survival than patients with persistent disease following repopulation of the marrow. Allogeneic bone marrow transplantation appears to be a promising method for treatment of certain patients with multiple myeloma.