The findings on MR imaging of 28 patients with spinal infection and 40 patients with spinal malignant disease were compared. Spinal infections involved one to 4 vertebrae, usually (23/28) 2 vertebrae. The posterior elements were involved with certainty in 26/40 patients with malignancy but in none with infection. In the latter group, the posterior elements might have been involved in 3/28. The intervertebral disk between the infected vertebrae was involved in 26/28 patients and 21/28 had a paravertebral mass. Spinal malignancies affected the vertebrae alone in 19 patients and paravertebral extension was found in 21/40 patients. The intervertebral disk was involved only in one patient with malignancy. The differences in the distribution of the MR findings between spinal infection and spinal malignancy were highly significant (p < 0.001). The highest signal intensity of the infectious lesions on T2-weighted images was equal to or higher than that of the cerebrospinal fluid (CSF) in 26/28 patients. In contrast, the signal intensity of the malignant lesions was hypointense as compared to the CSF in 29/40 patients (p < 0.001). MR is a useful method for differentiating between infection and malignancy in the lower spine; T2-weighted images are especially valuable for differentiation.