CT, MRI and neurological features of 27 children with tuberous sclerosis were prospectively compared. Imaging studies were positive in 92.5% of cases. CT was more useful in detecting subependymal nodules, while MRI showed the number and location of cerebral cortical and subcortical lesions more accurately. Cortical lesions in the cerebellar hemispheres were present in 26% of patients. Gadolinium-DTPA used in 10 patients showed slight enhancement of the subependymal lesions in 80% of cases, probably representing active lesions with alteration of the blood-brain barrier. None of the cortical and subcortical lesions enhanced. Giant-cell astrocytomas were detected in 5 patients, the postcontrast CT and MRI studies improving their assessment. Unlike subependymal nodules, all tumors showed marked enhancement regardless of their size. Seizures were present in 96% of patients, mostly beginning before 1 year of age. There was no clear relationship between the radiological features and the neurological evolution of these patients. Therefore, it is not possible to establish a clinical prognosis based on the radiological findings. MRI is the procedure of choice in the diagnosis of tuberous sclerosis. When pre and postcontrast MRI are negative, CT is used to exclude small calcified subependymal nodules. MRI follow-up is required only when tumoral development is clinically suspected.