Aim: The aim of the present study was to evaluate the general characteristics, survival time and prognostic factors affecting the high grade glial tumor after radiotherapy and chemotherapy. Patients and Methods: Data of 166 patients were retrospectively analyzed. Included histopathologically confirmed cases were grade 3 anaplastic astrocytoma and grade 4 glioblastoma multiforme. Patients were treated with curative radiotherapy and simultaneous ± adjuvant Temozolamide. Results: 73% of the patients were male, 27% were female and the median age was 57 years. 21% were anaplastic astrocytomas, 79% were glioblastom multiforme. 40% of the patients were total, 49% of the patients were subtotally operated and 11% of the patients had only biopsy for diagnostic purposes. The median Karnofski performance score of the patients before radiotherapy was 90. 3-dimensional conformal radiotherapy was applied to 37% of the patients, 63% of the patients were treated with intensity-adjusted radiotherapy technique. Simultaneous Temozolamide was administered with 92% of patients’ radiotherapy. The median follow-up time was 15 months. Overall survival rates were 82 months for anaplastic astrocytoma and 15.5 months for glioblastome multiforme (p <0.001). Overall survival rates at 1, 2, and 5 years were 77%, 59%, and 55% for anaplastic astrocytoma and 59%, 33%, and 4% for glioblastome multiforme, respectively. Median overall survival in patients aged <50 years was 39.3 months, while age ≥50 years was 12.4 months (p <0.001). Overall survival according to operation pattern was 33.2 months in total exposures, 13.8 months in subtotal resections, and 4.9 months in biopsies (p = 0.00). Overall survival was 8.1 months with a performance of <70, while overall survival was 22.3 22.3 months with ≥70 (p = 0.00). Overall survival was 12.9 months in patients who underwent three-dimensional conformal radiotherapy and 21.5 months in patients undergoing intensity-adjusted radiotherapy (p = 0.005). Overall survival was 7.8 months when applied to radiotherapy dose <60 Gy and 21.7 months when given 60 Gy (p = 0.00). Median survival was 18.4 months and 7.2 months, respectively, using concurrent Temozolamide (p = 0.03). Conclusion: In conclusion, the patient’s diagnosis, age, operative form, performance, radiotherapy dose, chemotherapy usage and survival were positive and our results are compatible with the literature.