In this study, we assessed 11 patients who were definitively diagnosed with tuberous sclerosis complex (TSC) based on the accepted clinical diagnostic criteria (Roach, 1998). We compared the clinical and radiological findings of six adult-onset TSC cases (group A) and five child-onset TSC cases (group B). The prevalence rates of generalized tonic-clonic convulsions at onset, mental retardation, facial angiofibroma, and epilepsy were lower in group A than in B group. The number of cortical tubers and subependymal nodules on brain magnetic resonance (MR) and computed tomography (CT) images were also lower in group A. The number of cerebral white matter radial migration lines was similar in both groups. Cortical tubers were most frequently observed in the frontal lobe in both groups. The number of cortical tubers and subependymal nodules did not correlate with the presence of epilepsy or mental retardation. Extra-brain lesions in lung, kidney, and bone were recognized in both groups, and no specific lesions were noted in group A.