The effect of intravenously administered gadolinium DTPA on signal intensity of normal intracranial structures was analyzed in 25 patients. Magnetic resonance (MR) image enhancement with Gd-DTPA differs from image enhancement on computed tomography with aqueous iodinated contrast media. Marked contrast enhancement owing to Gd-DTPA was observed in the pituitary gland, infundibulum, cavernous sinus, cranial nerves, choroid plexus, and nasal mucosa. Enhancement was not visible routinely in the falx cerebri, tentorium cerebelli, dura, or rapidly flowing blood. The efficacy of Gd-DTPA in any individual MR study may be assessed by observing the signal intensity of the pituitary gland, pituitary stalk, or nasal mucosa.