This retrospective review included 133 patients with one or several of the following defects: diastematomyelia, neurenteric cyst, dermal sinus or cyst, meningeal malformation, sacral agenesis, tethering of the spinal cord, and lumbosacral lipoma. Physical evaluation readily identified most lumbosacral lipomas, as well as most cases of diastematomyelia since hypertrichosis over the defect was common. Some patients developed life-threatening clinical manifestations, e.g., meningitis due to a dermal sinus. On the basis of this retrospective review and a review of the literature, the clinical and therapeutic aspects of each defect are discussed.