Two patients with plasma cell dyscrasias, manifested by osteosclerotic bone lesions and small amounts of M protein, and a complicating multi-system disorder are described. Their features of severe sensory-motor polyneuropathy, organomegaly, endocrine dysfunction, anasarca, elevated CSF protein, and skin hyperpigmentation are similar to a clinical syndrome reported primarily in Japanese men. Two previously unrecognized findings--hyperprolactinemia and an unusual radiographic abnormality of fluffy, spiculated bony proliferation--may facilitate recognition of the syndrome. The relationship of these various manifestations to the plasma cell dyscrasia is unknown, but a number of possibilities are discussed.