Ovarian cyst is found in 32% of necropsies in neonates, and can be visualized during gestation by ultrasonography. The clinical evolution of these cysts is variable, but in most cases the prognosis is favorable. Ovarian torsion, bleeding, rupture, and peritonitis have been described as complications. We report a newborn girl with torsion of ovarian cyst. A cystic mass measuring 41.9x31.9 mm on left side of abdomen was identified at 32 weeks of gestation by fetal ultrasonography. Surgery was performed after birth.