We report on a case of subependymal giant cell astrocytoma(SEGA)in a patient with tuberous sclerosis(TSC)that presented with intratumoral hemorrhage and acute hydrocephalus. Initial treatment was external ventricular drainage to control the intracranial pressure;however, the tumor increased in size due to recurrent hemorrhage. Subsequently, the tumor was successfully removed via the transcortical-transventricular approach without neurological deterioration. Although intratumoral hemorrhage is extremely rare in patients with SEGA, subsequent acute hydrocephalus resulting from obstruction of the foramen of Monro will be fatal if prompt surgical treatment is not available. Careful and periodical radiographic examination of the central nervous system will be mandatory in patients with TSC, especially in those who have subependymal nodules(SEN)or SEGA around the foramen of Monro. Radical surgical removal should be considered before they become symptomatic.