Tailgut cyst is a rare lesion of developmental origin located in the retrorectal space, which usually presents as a multilocular cystic mass, It is usually found in adults, and neonatal cases are extremely rare. The authors report a tailgut cyst in a neonate that was found by prenatal ultrasonogram, which was like a teratoma in gross appearance. J Pediatr Surg 35:1833-1835. Copyright (C) 2000 by W.B. Saunders Company.