The lower thoracic and lumbar spine of patients with multiple myeloma was examined by magnetic resonance imaging (MRI), plain radiography, and bone scintigraphy. Three independent investigators evaluated the power of these diagnostic methods to detect bone lesions in 192 vertebrae from 18 patients and in 60 vertebrae from 7 controls. 41 foci with abnormal signal intensity were detected by MRI; X-ray films showed osteolytic lesions in 4 vertebral bodies; and bone scanning was positive in 2 cases. The superiority of MRI in detecting myeloma-associated focal bone lesions was statistically significant, and in one case the lesions were confirmed at necropsy. Deviations in shape and height of vertebral bodies were slightly more easily visible on radiographs. Early detection of imminent medullary compressions in 2 patients led to successful radiotherapy before symptoms appeared.