A 63-year-old male patient was admitted to the hospital after a six-month complaint of low back pain. Anemia, hypercalcemia and 5 to 18% giant abnormal binucleated plasma cells infiltrations in the bone marrow suggested a diagnosis of multiple myeloma. However, repeated serum and urine immunofixation electrophoresis failed to demonstrate any abnormal monoclonal band. Diagnosis of non-excretory myeloma was verified by immunocytochemical stains demonstrating intracellular kappa chain in these neoplastic cells. Some authors have claimed that there were fewer bone lytic changes, less bone marrow infiltration, more preservation of normal immunoglobulin but with more neurological presentations among non-excretors. However, this patient had severely generalized bone lytic lesions and high serum level of tumor necrosis factor. The former might be attributed to the latter. Literatures about multiple myeloma and the tumor necrosis factor are also reviewed.