PURPOSE: We describe our institution’s experience with seven patients who developed second brain tumors following cranial irradiation. METHODS: The median age at first irradiation was 8 years (range, 3-20 years). Initial diagnoses were two cases of germinoma, one non-germinomatous germ cell tumor (NGGCT), three cases of medulloblastoma, and one pineal gland tumor (pathology undetermined). All patients received craniospinal irradiation followed by local boost and the median dose to the initial tumor area was 54.0 Gy (range, 49.8-60.6 Gy). Four patients (two medulloblastomas, one germinoma, and one NGGCT) received chemotherapy. RESULTS: Second brain tumors were diagnosed a median of 114 months (range, 64-203) after initial radiation. Pathologic diagnoses were one glioblastoma, two cases of anaplastic astrocytoma, one medulloblastoma, one low-grade glioma, one high-grade glial tumor, and one atypical meningioma. Five patients underwent surgical resection with subsequent radiotherapy. One anaplastic astrocytoma patient received chemotherapy only following stereotactic biopsy. The meningioma patient was alive 32 months after total resection and radiosurgery for subsequent recurrences. Six patients died within 18 months and most deaths were due to disease progression. CONCLUSIONS: Most patients diagnosed with second brain tumors had received high-dose, large-volume radiotherapy with chemotherapy at a young age. Further studies are required to determine the relationship between radiotherapy/chemotherapy and the development of secondary brain tumors.