About 3% of myelomas are classified as non-secretory myelomas and lack M component in the serum or the urine by immunofixation electrophoresis. In two-thirds of these patients, there is slight elevation of serum free light chains. By immunohistochemistry, monoclonal light chains are detected in about 85% of non-secretory myelomas. The remaining 15% are true non-producers. The histologic, immunophenotypic, and molecular genetic features of non-secretory myelomas are similar to the classic cases. The response to treatment and prognosis is also similar for the two groups. Clinically, there is lower incidence of renal complications and hypercalcemia in non-secretory myelomas. The image shows sheets of immature plasma cells replacing normal bone marrow elements in a trephine biopsy from a myeloma patient.