Twenty-four patients with multiple myeloma received an allogeneic bone-marrow graft from HLA-compatible sibling donors (n = 23), or a twin donor (n = 1). Eighteen patients are alive, 1-36 months post bone-marrow transplantation (median 14 months). Ten of these patients had no signs of multiple myeloma as judged by immunoglobulins in serum, light chains in urine, or the percentage of plasma-cells in bone-marrow aspirate. Bone lesions on X-ray were mainly unchanged. Six patients died from transplant-related complications 3 weeks to 5 months post transplantation. One of these patients had severe acute graft-versus-host disease (aGVHD). In other patients aGVHD was a minor problem. Allogeneic bone-marrow transplantation appears to be a promising method for treatment of a selected group of patients with multiple myeloma.