Subependymal giant cell astrocytoma (SEGA) is the most common brain tumor that develops in 5-20% of patients with tuberous sclerosis complex. Although these lesions are slowly growing tumor, they can cause morbidity and mortality due to acute hydrocephalus because of their prevalent location near the foramen of Monro. Surgery has been the standard care for SEGAs demonstrating serial growth and symptomatic hydrocephalus. However, not all SEGAs are treatable by complete surgical resection. Gamma Knife stereotactic radiosurgery can be considered as a second option, but it has shown highly variable responses in patients with limited data. In recent years, drugs with novel mechanism, sirolimus and other mammalian target of rapamycin (mTOR) inhibitors have been found to reduce the size of SEGAs. We report a case of treatment of SEGA with gamma knife surgery which continued for two years without progression, even though surgical resection was done, finally.