The components of the intervertebral disk serve two purposes. The hydrophilic matrix is contained by circumferential rings of fibrocartilage (outer anulus) and Sharpey's fibers. The gellike hydrophilic matrix acts as a cushion between the vertebral body endplates by providing an even distribution of axial and rotational compressive forces. The construction and integrity of the intervertebral disk are assessed well by MR. The purpose of this pictorial essay is to show the in vitro and in vivo MR appearances of the normal and degenerated disk, and to correlate these MR changes with their respective histopathologic findings.