Gastric duplication cyst is a rare disease entity, especially in the adult population. We report a case of 33-year-old female patient who presented with epigastric pain, postprandial fullness and nausea for the past several months. Gastroendoscopy showed a submucosal mass with normal overlying gastric mucosa. Upper gastrointestinal series confirmed a extrinsic compression of mass in the fundus of the stomach. Endoscopic ultrasonography and computerized tomography demonstrated the lesion to be a cyst in nature. The surgical procedure consisted of total excision without violation of the gastric lumen. Gastric mucosa was found by the histologic study of the excised cyst.