Omental cysts occur rarely. Patients with Omental cysts usually present with abdominal distention and a painless abdominal mass. In children it may present as an acute abdomen due to intestinal obstruction. The most common physical finding of an omental cyst is a freely movable abdominal mass, which should be considered in differential diagnosis of these cases. The diagnostic procedures include ultrasonography and computed tomography (CT) scans. Complete excision of the cyst is considered as the treatment of choice. Recurrence and malignant deterioration of omental cysts are rare. We describe a 32- year-old female who presented with complaints of vague abdominal pain and distension. The patient underwent laparotomy with preoperative diagnosis of the ovarian cyst. The diagnosis of omental cyst was established by intraoperative findings. Thus, complete excision of the cyst was performed. The diagnosis was confirmed by pathological examination.