Some knowledge of MR theory is required to be able to achieve high contrast between bone metastases and normal marrow. Three factors are used in MR to diagnose bone metastases; fat-water distribution, artifacts induced by bone trabeculae, and uptake of contrast medium. Using MR-histological correlations based on specimens of the lumbar spine, and studies of patients, we explain the advantages and limitations of sequences studying fat and water (spin-echo T1, STIR, in- and out-of-phase gradient echo, fat presaturation), bone trabeculae (gradient echo with long TE), and the injection of contrast medium.