A 39-year-old patient with bilateral paralysis of the VI cranial nerve was studied. Numerous foci of intracranial osteolysis were discovered as well as on the right calvicle and several ribs. Two bone marrow aspirates gave results within normal limits. A biopsy of the lesion on the right calvicle led to the diagnosis of myelomatosis. Immunoelectrophoresis showed that paraprotein was not present in serum and urine. Immunofluorescence with antisera marked with fluorescein was negative in the diseased bone marrow. Treatment with melphalan and prednisone given alternately produced an improvement in all of the lytic lesions within several months; 20 months after treatment was started no new destructive bony lesions have appeared. There have been very few reported cases of non-secretory myeloma. In most of these cases the presence of immunoglobulins in the tumoral cells has been shown by immunofluorescence. The absence of the immunoglobulins, as described in our case, is extremely rare. Unlike most cases of non-secretory myeloma published to date, our patient has a favorable clinical course after treatment was administered.