Distinction between spinal tumors and infections is a frequent clinical dilemma. To assess the accuracy of magnetic resonance imaging in distinguishing between spinal tumors and spinal infections, 30 patients with proven spinal tumors or infections were studied. Magnetic resonance imaging correctly diagnosed spinal tumors and infections in 29 of 30 cases (97%): 21 of 22 tumors were correctly diagnosed, and 8 of 8 infections were correctly diagnosed. The following points were learned: 1) The most consistent finding of vertebral osteomyelitis was the involvement of the disc space and adjacent vertebral body with decreased signal intensity on the T1-weighted images and increased signal intensity on the T2-weighted images. On the contrary, the disc spaces in tumor cases were uninvolved and demonstrated normal intensities on both T1- and T2-weighted images. 2) Loss of definition of the vertebral endplate was more common with infection than with tumor. 3) Contiguous vertebral involvement was seen more frequently in infections than in tumors. 4) Soft tissue changes were quite helpful: fat planes were obscured diffusely due to edema in infection, whereas fat planes were frequently intact, or obscured only focally, in tumors. 5) Cord compression was accurately diagnosed by magnetic resonance imaging in both tumors and infections. Magnetic resonance imaging was found to be superior to other imaging modalities in its ability to detect tumors or infections early and in providing information on the bone, disc, soft tissue, and neural structures.