Background: This study aims to evaluate the diagnostic yieldof fiberoptic bronchoscopy in ruptured pulmonary hydatidcysts indistinguishable from pulmonary masses on imagingtechniques.Methods: Between January 2000 and January 2018, a totalof 45 consecutive patients (27 males, 18 females; mean age46.4±13.5 years; range, 23 to 78 years) who underwent fiberopticbronchoscopy to establish the definitive diagnosis followingradio-diagnostic procedures were retrospectively analyzed.Data including demographic and clinical characteristics of thepatients, preoperative diagnostic studies, bronchoscopic findings,and postoperative diagnosis were recorded.Results: Endobronchial hyperemia (n=42) and purulent secretion(n=34) are the most common findings of bronchoscopy. The mostspecific finding was the presence of pieces of cystic membranesin 23 patients. Scolices were seen in five patients in bronchialaspirate. In one patient, both pieces of cystic membranes andscolices in bronchial aspirate were detected. The preliminarydiagnosis of a hydatid cyst was made based on these findings in28 patients (62.2%) preoperatively. The definitive diagnosis of ahydatid cyst was confirmed through thoracotomy in all patients.Conclusion: Bronchoscopy is a particularly valuable methodin the definitive diagnosis of ruptured lung hydatid cysts.The definite diagnosis is based on the visualization of theendobronchial membrane during bronchoscopy or scolicesin the bronchial aspirate. It can be also used to preventcomplications such as bronchial dissemination and asphyxia dueto intra-bronchial membrane pieces.