The authors report on 2 cases of subependymal giant cell astrocytoma (SEGA) with intratumoral hemorrhage causing acute hydrocephalus, necessitating emergent resection of the tumor. They review the literature and present their insights on the management of SEGA showing growth on serial imaging. Intratumoral hemorrhage causing acute hydrocephalus can occur not only in the pediatric ages but also in the early 20s in patients with SEGA. Awareness of this sequela is considered to be important in addressing surgical timing. The authors suggest early resection of the lesions when the evidence of growth has been confirmed, to prevent possible morbidity and mortality.