It is shown a case of IgD myeloma, a rare type of myeloma having often an aggressive course. Besides to confirm clinical and laboratory aspects already known in literature, this case seems to make in evidence a rapid neoplastic proliferation kinetic, difficult to be controlled by conventional chemotherapy. The Authors show that the M component low concentration and the unbalance of the synthesis of the immunoglobulin heavy and light chains may confuse IgD myeloma with light chain myeloma.