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Objectives: To demonstrate the different pattern of failure after radiosurgery of the recurrent glioblastoma (rGBM) to two different target volumes of contrast enhancing lesion only with/without FLAIR abnormality. Methods: A total of 61 patients with rGBM were treated with fractionated radiosurgery (FRS) Between 2008 and 2012. All patients were diagnosed with recurrent GBM, including 3 patients whose tumors trnasformed to GBM. All patients received initial treatment with surgery followed by radiotherapy with temozolomide and treated with second-line chemotherapy before FRS. Radiosurgery Regimen A was 32Gy (8Gy x 4 within 2 weeks) to the contrast enhancing lesion only. Regimen B was 32Gy (8Gy x 4 within 2 weeks) to the contrast enhancing lesion and 24Gy (6Gy x 4 within 2 weeks) to the area of new FLAIR abnormality delivered concomittantly. Results: The median overall survival after primary diagnosis was 28 months for patients with GBM and 132 months for patients with initial grade 3 gliomas. The median survival after SRS was 10 months. The median progression-free survival after SRS was 5 months. Overall, 62% (38/61) recurred during the follwoup period. Tumor control rate was 17% (7/40) in regimen A and 33% (7/21) in regimen B (p = 0.081). Regimen A had 67% (27/40) locoregional failure and 15% (6/40) distant failure. Regimen B showed 52% (11/21) locoregional failure and 14% (3/21) distant failure. No acute or long term toxicities were attributable to FRS of either regimen. Conclusion: Both FRS regimens were safe and effective for salvage therapy of recurrent GBM. FRS to the contrast enhancing lesion and flair abnormality appear to improve tumor control, and there is trend to reduce the regional tumor progression. Based on this finding, a prospective study is ongoing to further clarify the optimal role of FRS in the treatment of recurrent GBM. Disclosure: No significant relationships. [ABSTRACT FROM AUTHOR]