Multiple myeloma commonly produces neurologic symptoms when it involves the cranium or vertebrae, but rarely invades the CNS or meninges. Intracranial or intraspinal myeloma without lesions in the adjacent bone is extremely rare. To our knowledge, there are only ten reported cases of isolated myeloma in dura and/or brain, and only two limited to the leptomeninges. We wish to report the third case of isolated leptomeningeal myeloma. Both myeloma cells and abnormal globulins were present in the CSF, but absent from serum and bone marrow. Analysis of these 13 cases in dura, brain, or leptomeninges strongly supports the concept that abnormal proteins do not reach the CSF from the serum but are produced by myeloma cells in situ.