We report a case of simple renal cortical cyst in neonate with review of literature. A female infant weighing 3, 400 g was delivered. Because of single umbilical artery found on physical examination, abdominal ultrasonogram was performed. A 3 mm sized renal cortical cyst was found in right kidney, but no associated symptoms or signs including renal functions were found. Follow up ultrasonogram was performed a month later and it was spontaneously disappeared.