From our study of eight pineoblastomas and five pineocytomas and a review of the literature, we have described two clinicopathologic syndromes that characterize these neoplasms. Pineoblastomas highly resemble the medulloblastoma-neuroblastoma group of tumors and occur mostly in young people. The tempo of progression of the disease is fast, the length of illness is short. These are infiltrating neoplasms that commonly spread via the cerebrospinal fluid. They are radiosensitive. Histologically they are also similar to the medulloblastoma-neuroblastoma group and are characterized by the scarcity of cytoplasmic processes and by the Homer Wright rosette. They contain giant cells. Pineocytomas are tumors of adults. The tempo of progression of the disease is slow, and the length of illness is long. They expand by compressing the surrounding tissues. Histologically they are characterized by the abundance of cytoplasmic processes and by the pineocytomatous rosette. They contain giant cells. Areas composed of neoplastic gangliocytes and astrocytes in various combinations are common variants in some of these neoplasms.