Metrizamide (Amipaque) is a new water-soluble contrast agent for use in the intrathecal space. Extensive animal and clinical studies have demonstrated its low toxicity. The advantages to the use of metrizamide include the fact that it is miscible with cerebrospinal fluid and can fill narrow spaces, is sufficiently radiopaque to outline delicate structures within the central nervous system, is completely resorbed from the subarachnoid space, and, to date, has not been implicated in the formation of adhesive arachnoiditis. Application of metrizamide to the evaluation of neurologically diseased patients has included myelography, intracranial cisternography, and ventriculography, as well as various techniques in conjunction with computerized tomography. These various uses of metrizamide are discussed together with some indications and advantages. Metrizamide has now replaced Pantopaque and gas as the most commonly used intrathecal contrast agent at the University of Texas Health Science Center at Dallas.