Neuroblastic tumors are the most common extracranial tumors of childhood. They arise from embryonal cells committed to the development of the sympathetic nervous system. In vivo and in vitro observations have shown that neuroblastic tumors appear to recapitulate the development of differentiating sympathetic neurons and chromaffin (neuroendocrine) cells of the sympathetic nervous system. This suggests that the origin of neuroblastic tumors resides as a block in the process of differentiation. This article summarizes the experimental data accumulated over the last three decades, which has provided some clues to the cellular origin of such tumors. In order to identify the cellular origin of these tumors, the embryology of the sympathetic nervous system is first reviewed and any archeological rests of normal development in the tumors are then discussed.