Objective: We report a case of giant diaphragmatic hydatid cyst which ruptured spontaneously into the intrapleural space in a patient with coexistent giant hepatic hydatid cyst. Clinical Presentation and Intervention: A 62-year-old female was admitted for dyspnea, nausea, vomiting, and right thoracic pain. Clinical findings, laboratory and radiological examinations including multislice computed tomography scan were consistent with the diagnosis of a giant diaphragmatic hydatid cyst which ruptured into the intrapleural space. Surgical intervention was performed through thoracotomy and phrenotomy in a one- stage operation for both cysts. Conclusion: This case shows that hydatid cysts of the diaphragm can rupture into the intrapleural space spontaneously. One- stage operation through thoracotomy may be successful for the surgical intervention for diaphragmatic hydatid cysts with coexistent hepatic cyst. Copyright (c) 2007 S. Karger AG, Basel.