The detection and characterization of intra-axial tumors in the adult have been greatly improved with the advent of magnetic resonance (MR) imaging, particularly when combined with paramagnetic contrast enhancement. MR imaging allows tumor localization along with evaluation of edema, tumor margins, intrinsic signal intensity on T1- and T2-weighted sequences, and the presence or absence of enhancement. Consideration of these characteristics together with pertinent clinical history forms the basis of a reasonable differential diagnosis. The article summarizes the MR imaging characteristics and pathologic findings of the major intra-axial tumors of adults with emphasis on differential considerations.