The primitive neuroectodermal tumors (PNETs) of Hart and Earle constitute an important fraction of pediatric brain tumors that are clinically characterized by their aggressive behavior. In 1983, Rorke expanded the term "PNET" to include all small cell embryonal neoplasms of neuroectodermal origin, regardless of the location of the tumor. More recently, Dehner also proposed the terms "central" and "peripheral" PNETs, and the provocative concept of "PNET" has now come to encompass a diverse group of tumors in both the central and peripheral nervous systems. The acronym "PNET" has thus become a confusing and controversial term in the diagnosis and classification of pediatric embryonal tumors. We reviewed ten papers concerning the various aspects of PNETs.