Gastric diverticula are a rare condition; they are divided into true diverticula, which are congenital, and pseudodiverticula, which are acquired. True diverticula are usually located in the posterior fundus wall, below the esophagogastric junction, and appear on abdominal computed tomography as a cystic mass that is commonly taken for an extra digestive mass, especially adrenal mass. We report the case of an asymptomatic 24-year-old female patient with gastric diverticulum who was mistakenly diagnosed in ultrasound with a renal mass.