The MR findings in eight patients with intracranial manifestations of tuberous sclerosis are reported. There were subependymal lesions in seven patients and peripheral lesions (i.e., cortical and subcortical) in all patients. All lesions were supratentorial. We emphasize two findings that have not been previously stressed. The signal intensity patterns of the subependymal lesions varied from patient to patient, but in all patients receiving intravenous contrast medium, the majority of these lesions enhanced. Although this finding may signify early breakdown of the blood-brain barrier with potential for lesion growth, the high frequency of enhancement challenges earlier concepts of equating this phenomenon with existence of actively growing giant cell astrocytomas. The peripheral lesions were more numerous than subependymal lesions. These lesions were nearly always hyperintense in the proton density weighted and T2-weighted images. Most notable is the fact that, in half of the lesions, signal intensity was also elevated in the T1-weighted image, an observation that has not been emphasized in previous reports. Although not pathologically confirmed this signal pattern may represent early stages of calcification within these lesions. Finally, unlike subependymal lesions, none of the peripheral lesions showed contrast enhancement.