Tuberous sclerosis is an autosomal dominant disorder in which patients develop hamartomatous lesions in many different organs, most commonly in the brain, heart, kidney and skin. Two TSC-determining loci have been mapped to chromosomes 9q34 (TSC1) and to 16p13.3 (TSC2). These genes act as tumor suppressor genes, but the mechanism of hamartomatous growth is not completely understood. Recently, the prevalence of TSC is increased by new developments such as the imaging techniques. However, in some cases, physicians were not able to diagnose some TSC individuals because they were asymptomatic or because their symptoms or signs were various. In this review, we present the clinical features and molecular analysis.