Hydatid cystic disease is still a significant clinical problem in endemic countries. Hydatid cysts are usually located in the liver and lung. The resulting large cysts in the lung are a special clinical entity called giant hydatid cysts. We present a case of this rare entity: An 18-year-old woman presented with three month history of hiccups and progressive dyspnea. Chest X-ray revealed a very large homogenous opacity of the left lung. A diagnosis of giant hydatid cyst was made intra operatively; the patient was treated surgically using cystotomy and capitonnage without post-operative complications. This report illustrates that the hydatid cyst of the lung may occasionally present with signs of mediastinal compression.