The purpose of this study was to evaluate the performance of the new Graded Prognostic Assessment (GPA) index, which was recently developed from data in the Radiation Therapy Oncology Group (RTOG) database, in patients treated with surgical resection of brain metastases and postoperative whole-brain radiotherapy. The authors analyzed 64 patients and assigned each patient to each of the four indices previously evaluated by the RTOG (recursive partitioning analysis class, Score Index for Radiosurgery, Basic Score for Brain Metastases and GPA). The present data confirm the validity of the scoring systems in surgically treated patients. Each of the four indices splits the dataset into prognostically different groups; in the GPA groups, median survival was 18.9, 9.8, 5.5, and 3.7 months, respectively (p<0.05). In conclusion, these results confirm the validity of the GPA index in a patient population that previously has not been assessed with this new tool.