Skeletal radiography, bone and bone marrow scintigraphy have been performed in 130 patients with plasma cell dyscrasias (119 multiple myeloma, 9 MGUS and 2 Waldenström disease). Our results confirm: 1) that radiography is much more sensitive than scintigraphy in the identification of the lesions typical of myeloma, but in the first stage bone scintigraphy and especially bone marrow scintigraphy are more sensitive than x-ray for the detection of regions affected by focal lesions; 2) that bone scintigraphy is of particular value in detecting some abnormalities in specific sites not fully visualized by x-ray; 3) that bone marrow scintigraphy is a valuable diagnostic tool in the early stage of myeloma, especially for evaluating the progression of the disease, because it is able to demonstrate not only focal lesions, but also bone marrow expansion. We believe that bone marrow scintigraphy may be a useful technique in the early diagnosis and follow-up of multiple myeloma, particularly in the detection of unusual forms (i.e., "smouldering" myeloma), but it remains only an "additional" technique for bone imaging.