This study evaluated the diagnostic value of contrast enhancement in consecutive adults referred for cranial magnetic resonance imaging (MRI). All of the 112 participating patients underwent two sets of studies, first without and then with a contrast medium. Three neuroradiologists independently reviewed the information for each patient. Contrast enhancement contributed diagnostically useful information in 75% of cases: in 4% because undiagnosed lesions became apparent, in 26% because more information was obtained regarding the size, extent or margins of a lesion and in 45% because the lack of contrast enhancement in the area of interest allowed more confident exclusion of disease in patients with compelling clinical findings or demonstrated the nonaggressive nature of a lesion apparent with unenhanced MRI. The authors conclude that contrast enhancement is diagnostically useful for most patients referred for cranial MRI. Although the proportion of cases in which contrast enhancement was useful was much higher than in previous studies conducted in the United States, the authors believe that this finding is due to the high prevalence of disease in the population referred to this Canadian MRI centre.