The appropriate radiation dose and field for the treatment of intracranial germinoma were investigated in 33 patients. Recurrences were observed in 4 cases treated with local field irradiation only, and all of them were recognized at the margin of the radiation field or under the dose (less than 25 Gy) area. This suggests that whole cranial irradiation (dose of 25 to 30 Gy) should be added even if the tumor is solitary. The effective dose for cerebrospinal dissemination appears to be 25-35 Gy, but prophylactic CNS irradiation seems unnecessary for patients who have not undergone surgical procedures. Changes in mental status were seen in 5 patients (26.3%). Doses of over 59 Gy may be related to this complication.