Abstract： Objective To evaluate the effectiveness and side effects in sibling and unrelated HLA identical allogeneic hematopoietic stem cell transplantation for multiple myeloma patients under 45-year-old at early stage. Methods Three patients with multiple myeloma ranged from 38 to 44-year-old received two courses of chemotherapies and achieved partial remission. Sibling HLA identical allogeneic hematopoietic stem cell transplantations were underwent in case 1 and 2, and unrelated were in case 3. The conditioning regimens for case 1 and 2 included fludarabine, busulfan plus cyclophosphamide, and of case 3 included modified busulfan, cyclophosphamide plus antithymocyte globulin. Cycloporine A combined with methotrexate were used to prevent GVHD in the case 1 and 2, and methotrexate, mycophenolate and cycloporine A were used in case 3. Results All patients achieved full donor chimerism without graft failure. Grade Ⅱ acute GVHD and extensive chronic GVHD were found in case 1, but not in case 2 and 3. The period of follow-up of case 1, 2 and 3 were 48, 27 and 6 months, respectively, and all of them were alive with no signs of relapse. Conclusion The multiple myeloma patients under 45-year-old underwent sibling and unrelated HLA identical allogeneic hematopoietic stem cell transplantation at early stage after chemotherapy remission have the low treatment-related mortality, high complete remission rate and may prolong long-term survival.