Gastric duplication cysts (GDCs) are uncommon developmental anomalies found primarily in children, being rarely seen in adults. Duplications can occur anywhere in the intestinal tract from the mouth to the anus. Accurate diagnosis of cysts before resection is difficult even using the most advanced imaging techniques. In this report, we present and discuss a case of GDC in a 25-year-old man treated laparoscopically. Patient admitted to our department with complaints of epigastric pain and swelling. Magnetic resonance imaging performed for accurate characterisation showed a 4 cm × 4.5 cm cystic lesion, with heterogeneous signal intensity on T2-weighted images, located in the posterior wall of the stomach. Pre-operative differential diagnosis including gastrointestinal stromal tumour (GIST) was made according to radiological findings. Patient underwent surgery and cyst resected laparoscopically. Histopathological examination suggesting duplication cyst. GDC can easily be mistaken for a GIST, and the clinician as well as radiologist must maintain a high degree of suspicion.