Sixty-eight patients with plasmacytic neoplasia and osteosclerotic lesions were analyzed. Men predominated in this series. Mean age was 55.3 years and 26 patients were younger than 51 years at diagnosis. Early onset of disease was statistically different from multiple myeloma in general. Thirty patients had peripheral polyneuropathy and often neurological manifestations preceded other symptoms. Skeletal pain was less common, whereas hepatomegaly, splenomegaly, and lymphadenopathy were more common than in myeloma in general. Incidence of azotemia, hypercalcemia, high ESR, and anemia was lower than in myeloma. In one fourth of the patients, the number of skeletal lesions did not exceed three. Mean survival was less than 20 months from first symptom and 12 months from diagnosis. Mortality was related sometimes to polyneuropathy. Thus, in several aspects, plasmacytic neoplasia with osteosclerotic lesions is different from the classical multiple myeloma.