A 54-year-old woman underwent a left pneumonectomy for monolateral congenital pulmonary cysts, complicated by a pleural empyema without bronchial fistula, in the late postoperative period. The pleural empyema was evacuated and managed by means of a small thoracic drainage. Three months after discharge the patient noticed the presence of ingesta in the pleural washing fluid. Diagnostic and operative procedures in this rare case of non malignant, non traumatic gastropleural fistula are described.