A 2-month-old girl with a supratentorial primitive neuroectodermal tumor (PNET), which extended into the skull, is herein presented. The patient underwent total removal of the tumor and also received a course of postoperative chemotherapy. After a follow-up period of 12 months, the infant is alive without recurrence. Histologically, the tumor was composed of poorly differentiated neuroectodermal cells, and these neoplastic cells showed a mild immunohistochemical reaction for GFAP and synaptophysin, and a moderate reactivity for neuron specific enolase and vimentin. In addition, a moderate level of immunoreactivity for HBA71 antigen (p30/32M1C2), which is the product of the M1C2 gene and is found in peripheral PNETs but not in central PNETs, was noted in many neoplastic cells. Although this tumor was located intracranially, it may be classified as a peripheral PNET.