Gastrointestinal stromal tumor located in the mediastinum is a rare pathology, that may cause symptoms typical for primary tumors of the pleural cavity. Thoracic GISTs are mostly tumors of the esophagus, howe ver, they can originate from other organs. We reported a case of surgical resection of stomach giant GIST, pro-lapsing into posterior mediastinum forming paraeso-phageal hernia.