The sequential appearance of two different brain tumors in the same patient without intervening radiation or chemotherapy is a rare event, most often seen in hereditary cancer syndromes. We present one such case of sequential tumors, along with their molecular analysis. A 17-year-old male presented with a pilocytic astrocytoma arising in the fourth ventricle at the pontomedullary junction. Six and one half years later, a pineoblastoma was discovered in the fourth ventricle, rostral to the first tumor site. Both tumors were treated by gross-total surgical resection. Following resection of the pineoblastoma, the patient underwent craniospinal irradiation and systemic chemotherapy. Single-strand conformation polymorphism analysis showed that the patient had neither a germ-line mutation nor a somatic tumor mutation in the p53 tumor suppressor gene. Coupled with the lack of a family history of cancer, these data suggest that these were not manifestations of Li-Fraumeni syndrome, but rather two sporadic tumors which arose via a p53-independent mechanism.