Ectopic splenic tissues left after a previous splenectomy can masquerade as a gastro-intestinal stromal tumour (GIST).Splenectomy was carried out for a 17-year-old girl with a giant epithelial cyst of spleen. Four years later, an upper endoscopy carried out for dyspepsia revealed two sub-mucosal lesions at the posterior wall of the gastric fundus. Computed tomography diagnosed a GIST. At operation, a dump-bell shaped extragastric mass was excised. Histology showed normal splenic tissues.Giant epithelial cyst of spleen is rare. It is even rarer for ectopic splenic tissues left after splenectomy to masquerade as a GIST.Ectopic splenic tissues should be included as a differential diagnosis in a patient who has a history of splenectomy presenting with a sub-mucosal gastric tumour.