Children (20) with tuberous sclerosis were examined by computer tomography (CCT). The test is useful to detect cerebral involvement with great certainty. The method is especially helpful in the early diagnosis of the disease. This offers the possibility of giving early genetic advice. Characteristic CCT scan abnormalities in tuberous sclerosis are multiple densities in the walls and the roof of lateral ventricles. This specific finding can be seen prior to the occurrence of calcifications in standard roentgenograms.