Dr. Nathaniel I. Berlin: Multiple myeloma is a disease of the plasma cells, characterized by lytic lesions in the bone and by the production of abnormal proteins, for which there is no satisfactory therapy. New approaches utilizing advances in protein chemistry, immunology, and biology have made possible a number of studies of the malignant plasma cell in man and in mice. Plasma-cell tumors have been produced in mice—experimental animal tumors that are comparable to multiple myeloma in man. In preparing this program I have selected from a larger number of studies in the National Cancer Institute those which illustrate selected