Magnetic resonance (MR) imaging examinations of the lumbar spine and clinical and laboratory findings in 32 patients with multiple myeloma were reviewed. On T1-weighted images, signal intensity (SI) of the vertebrae approximated that of muscle in 14 cases and was intermediate (between the SIs of muscle and fat) in 18. Definite foci of decreased SI were seen in eight cases (25%), and foci of increased SI, representing fatty infiltration, were seen in 12 (38%). On T2-weighted images, SI approximated that of muscle in 17 cases and was intermediate in 15. Definite foci of increased SI were seen in 17 (53%). Of 38 vertebral compression fractures (including 18 in nine additional patients), foci of abnormal SI consistent with tumor on either T1- or T2-weighted images were seen in 19 cases (50%). There was no correlation between MR imaging findings and laboratory or bone marrow findings. Foci of presumed tumor were better or exclusively shown on T2-weighted images in 11 of 17 patients (65%) with identifiable focal disease. Other suggestions of multiple myeloma on T1-weighted images may be the absence of fatty replacement or a generalized decrease in SI.