Gastrointestinal tract duplications are congenital malformations rarely seen in adulthood. Gastric duplications (GD) represent 2–9% of it. Malignant transformation of GD is a rare complication described in the literature. We present the case of a 43-year-old man, who presented an abdominal mass and an elevated CEA level. A total gastrectomy was performed and the histological examination described a gastric duplication cysts (GDC) without malignant transformation. It is not the first case of elevation of CEA in GDC without evidence of malignancy described in the literature. Some authors think that GDC are premalignant lesions that envolve with the time to carcinomas. It is recommend that once the GDC is diagnosed to remove surgically the entire cyst even if the patient is asymptomatic.