To evaluate the feasibility and efficacy of a autologous stem cell transplantation followed by a Melphalan/ Fludarabine based dose-reduced allograft from HLA-identical and HLA-compatible unrelated donor in patients with Multiple Myeloma. In those with non complete remission DLI and/ or new agents such as Bortezomib, Thalidomid or Lenalidomide can be used to upgrade remission.

Inclusion Criteria:

• Multiple Myeloma Stadium II / III acc. to Salmon and Durie
• signed informed consent
• adequate organ function prior autologous respectively allogeneic SCT
• availability of HLA-identical related or unrelated donor
• availability of at least 2 x 10^6 CD34+ cells per kg BW of recipient for the autologous SCT and at least 3 x 10^6 CD34+ cells for allogeneic SCT
• for MRD-SCT: 18-66 years; for MUD-SCT: 18-55 years
• at age <55 years existence of risk factors that make an myeloablative allogeneic transplantation to risky
• consent of donor to give DLI

Exclusion Criteria:

• severe heart insufficiency
• cardiovascular diseases or severe concomitant diseases
• active infections that need antibiotic therapy
• positive for HIV or hepatitis
• malign secondary disease
• limited liver function with total bilirubin > 1.5 ULN
• increased transaminase > 3 ULN
• increased serum creatinine > 2 mg/dl
• pregnant or lactating women
• known hypersensitivity to Fludarabine or Melphalan
• participation in another trial