A prospective clinical study was performed in 70 consecutive patients with known or strong clinical suspicion of acute or relapsing multiple sclerosis. The study was designed to compare the results of standard computed tomography and high-volume contrast-delayed scanning for the detection of enhancing lesions. In 39 cases with clinically definitive multiple sclerosis, the conventional enhanced scan was positive in 25 cases and the high-volume delay scan in 32. The high-volume enhanced scan added information in 23 of these 32 cases. In 21 cases, suspicious of multiple sclerosis but not clinically confirmed, the standard enhanced scan was positive in two cases and the high-volume delay scan in five. In these cases, computed tomography was definitive in establishing the diagnosis by showing clinically unsuspected brain lesions. In 10 cases in which the disease was eventually excluded, the scans were negative in all instances. For the first time, by the high-volume delayed technique, enhancing plaques in the cortical gray matter and in the gray/white matter regions were demonstrated. This technique is a very useful diagnostic tool, not only for morphologic assessment when multiple sclerosis is known, but for the positive diagnosis of this disease when the first clinical presentation is diagnostically uncertain.