Myelomatous bone disease affects about 90 % patients with multiple myeloma and solitary myeloma as well. In initial stage it is manifested as osteopenia with osteoporosis or osteolytic foci, pathologic fractures followed by neurologic complications Ethiopathogenitically a role is played by cytokine interactions with local chemokines produced by myeloma cells and activated stromal and hemopoieticc cells (osteoblasts, monocytes, macrophages) resp. From the TNF-a family glycoprotein complexes are liberated (RANK-L), which support activation and proliferation or are inhibitory (osteoprotegerins). Similarly in the family TGF-R several izotypes of antiinflammatory cytokines are known (the most important is TGF-(31 and the morphogenetic protein-2), which have a fibrotizing effect in bones, because the produced osteoid is insufficiently mineralized. The effect is a pathologic remodelation of the skeleton. In the diagnosis of multiple myeloma the immunological knowledge is used in the initial diagnosis (immunophenotypization, follow up of TNF-a, TGF-(31, IL-1, IL-6 etc). Important are also biochemistry values of increased osteoresorption (changes of calcium, parathormone, excretion of collagen fission products, osteocalcin, the bone alcaline phosphatase). In the following part the authors inform about favourable results of long-term treatment with bisphosphonates (Bonefos, Ibandronate) in combination with anti-tumor chemotherapy in 364 patients. During a 15 years observation period medián survival of 94 months with a 35 % probability of 10 year survival was achieved with a significant decrease of bone complications in 58 % compared to 14 % in the placebo group.

        Key words: Ethiopathogenesis of multiple myeloma - Bisphosphonates in therapy of multiple myeloma - Cytokines