Purpose : To evaluate the frequency, location, and signal intensities of parenchymal (cortical and subcortical) tubers and white matter lesion, as seen on MR images of patients with tuberous sclerosis.Material and Methods : Twenty patients diagnosed on the basis of clinical and MR findings as suffering from tuberous sclerosis, were retrospectively reviewed. Their ages ranged from 6 days to 21 years (mean, 5.2 years), and they were divided into two groups according to age : under 18 months (n=9) and over 18 months(n=11). We analyzed the frequency, location, and enhancement patterns of tubers and white matter lesions, and the difference of signal intensities between cortical and subcortical tubers according to age.Results : Cortical tubers were detected in11 patients (55%), subcortical tubers in 18 (90%), and white matter lesions in 16 (80%). Subcortical tubers were more frequently noted than cortical tubers and the two types did not always accompany each other. Cortical tubers were most commonly located in the frontal lobe(10/11), followed by the parietal lobe(2/11), and temporal lobe(2/11). Subcortical tubers were also most commonly located in the frontal lobe(17/18), followed by the temporal lobe(10/18). White matter lesions were also frequently observed in the frontal lobe(13/16) and were related to the location of parenchymal tubers in 12 of 16 white-mater lesions. There were no lesions in the cerebellum. The signal intensities of cortical and subcortical tubers were different in all patients. Those of subcortical tubers showed no significant difference between the two age groups, but in patients under 18 months, signal intensity on T1WI tended to be high(5/6), and on T2WI, tended to be low(5/6). In 15 patients, Gd-DTPA enhanced MR images showed no demonstrable enhancement, except in one case involving white-matter lesion.Conclusion : Both cortical and subcortical tubers were commonly located in the frontal lobe, but the latter were more frequently observed than the former. Subcortical tubers did not always accompany cortical tubers, and on MR imaging, the signal intensities of the two types were different in all cases. Differentiation of cortical and subcortical tubers by MR imaging may therefore help analyze the parenchymal tubers seen in tuberous sclerosis.