Abnormal spinal embryogenesis is quite commonplace. While greater than 90 percent of these errors of embryogenesis leads to occult spinal dysraphism with minimal neurologic or orthopedic sequelae, there is a significant minority of these anomalies which leads to the formation of the so-called 'congenital tumors of disordered embryogenesis'. The purpose of this article is to discuss the embryology, presentation, diagnosis and management of the spinal dysraphic states with particular emphasis on those errors which lead to mass lesions in the spinal canal such as dermoids, epidermoids, lipoma/lipomyelomeningocoele and neurenteric cysts. We also include lesions such as dermal sinus tracts and thickened filum terminale in our discussion with particular emphasis on their relationship to the tethered cord syndrome. Proper surgical management of these various conditions necessitates a thorough understanding of their embryologic etiology and the anatomic/physiologic ramifications that such lesions have on the developing spinal cord.