In this retrospective study, the result of 36 adult patients with differantiated astrocytoma were treated at Saint Luke's Radiothera py and Clinical Oncology center between 1967-1979 and at Gülhane Medical Faculty Hospital between 1975-1984 are presented. The 5 year survival rates were % 52 for the whole group, °7o 48 for the adult cerebral and two of four patients with the adult cerebellar differantiated astro cytomas are Living 5 years without disease. 6 patients with adult cerebral astrocytomas had grossly complete excision and postoperative radiation, (<% 50 of patients received paliative dose radiation) Of these only 31 % survived 5 years. There fore, it is suggested that postoperative radical dose radiotherapy should be given to all patient with adult diffuse type cerebral astrocytomas who receive grossly complete excision. 24 patient who received incomplet tumor resection and postoperative radiotherapy, survived 43 % 5 years. Those treated with radiotherapy alone, 2 of 5 cases are still living and completed 83. and 94. months followed-up with none active disease. In order to show the role of postoperative radiotherapy, we reviewed the cases in the literature and divided patient in two group. Patients with fist group who had resection only and patients with second who received resection plus radiotherapy. Patient who received postoperative radio-therapy had better survival rates in 5 and 10 years. (5 year survival rates 24 % vs 41 % respectively, (P:0.001) 10 year survival rates were 16%vs 28 % respectively, (P:0.30) .