Seventy-three patients with clinically suspected central nervous system abnormalities (44 intracranial, 29 medullospinal) were studied with magnetic resonance (MR) imaging before and after administration of nonionic gadodiamide injection. MR imaging showed intracranial lesions in 37 patients. Eight patients had spinal tumors, and 21 had disk disease. Structural abnormalities were shown in 37 of 44 head studies and in all 29 spine studies. Lesions enhancement was seen in 31 head studies and 28 spine studies, and distinction of lesion(s) from associated edema was possible in 10 head studies and in one study of intrinsic cord tumor. Administration of gadodiamide injection provided improved definition of lesion borders in 19 of 44 head studies and 26 of 29 spine studies. The use of the contrast agent changed the diagnosis that was based on the unenhanced images in nine head studies and 13 spine studies. Early postcontrast, T1-weighted spin-echo images of postoperative spines were adequate in distinguishing epidural scar (enhancing) from herniated disk (nonenhancing). The contrast agent was well tolerated, and no drug-related adverse events occurred.