A 15-year-old boy was diagnosed with choroid plexus carcinoma (CPC) of the right lateral ventricle. His metastatic work-up was negative. After complete macroscopic resection of the tumor, the patient was treated with chemotherapy consisting of vincristine, cisplatin, etoposide, and carboplatin, followed by radiotherapy for a total dose of 34.2 Gy on the whole craniospinal axis plus a boost of 19.8 Gy at the tumor region. The patient remained in complete clinical and radiologic remission over the next 5 years when a secondary malignant tumor, glioblastoma multiforme, a rare complication of the treatment of CPC, was diagnosed. This case reflects the necessity of thorough follow-up in long-term survivors of CPC.