Magnetic resonance (MR) imaging was performed on 64 patients with 109 vertebral compression fractures, the cause of which could not be determined from plain radiographs. Twenty-five fractures were due to malignancy; 84 were caused by a benign process. In 22 of the 25 fractures caused by malignancy, MR images showed complete replacement of normal bone marrow, whereas 47 of the 61 benign fractures without history of trauma had complete preservation of normal bone marrow. The remaining 14 benign fractures had incompletely preserved bone marrow in a regular pattern. In two of the three remaining malignant fractures, the bone marrow replacement also was incomplete but with an irregular pattern. In cases of recent trauma or primary bone marrow abnormalities, the configuration and signal of remaining bone marrow were not useful in differentiating among malignancy, osteoporosis, and other benign processes. When criteria based on complete loss or preservation of marrow and marrow configuration in cases of incomplete loss were used, the accuracy in differentiating benign from malignant fractures was 94%. MR imaging may be a useful adjunct in differentiating benign from metastatic fractures and may provide information not available with other imaging methods.