A multicenter prospective trial was conducted (Maligue Keimzelltümoren [MAKEI] 83/86/89) to assess outcome in intracranial germinoma after treatment with radiotherapy alone at reduced doses. Between 1983 and 1993, 60 patients with histologically (n = 58) or cytologically (n = 2) confirmed germinoma were enrolled onto the study. Patients received radiotherapy alone (craniospinal axis/local boost). In the MAKEI 83/86 study (involving 11 patients), the dose to the craniospinal axis was 36 Gy and the dose to the tumor region was 14 Gy. In the MAKEI 89 study (involving 49 patients), doses were 30 and 15 Gy, respectively. Median patient age was 13 years (range, 6 to 31 years). Complete remission was achieved in all patients. The estimated (Kaplan-Meier) 5-year relapse-free survival rate was 91.0% +/- 3.9% at a mean follow-up of 59.5 months (range, 3 to 180 months); the estimated overall survival rate was 93.7% +/- 3.6%. Relapse occurred in five patients 10 to 33 months (mean, 18.4 months) after diagnosis (one patient developed a spinal canal metastasis and underwent salvage radiotherapy and chemotherapy; four patients had metastases outside the CNS and underwent salvage chemotherapy alone). Four patients died: one died from disease, two died from therapy-related complications, and one committed suicide. Acute complications with long-lasting sequelae were tumor or surgery related (three cases of blindness, six of reduced vision, two of hemiparesis). Psychosocial development was normal in the majority of patients. Radiotherapy directed toward the craniospinal axis or tumor site alone at decreased dose levels is effective. To reduce the risk of late side effects, further attempts to decrease total doses are justified. In cases of recurrent disease, chemotherapy administered outside the CNS is the treatment of choice.