Hydatid cyst (HC) is a parasitic disease that may involve many organs, especially the lung and the liver. Pulmonary artery location of the hydatid cyst is extremely rare, but it may cause life-threatening complications. We report a case of a hydatid cyst that completely filled the left main pulmonary artery and its distal part without cardiac involvement. Thoracic computed tomography showed filling defects in the pulmonary arteries. Endobronchial ultrasound was performed for differential diagnosis and it showed a cystic lesion. Hydatid cyst-specific IgE and hem agglutination test results were positive. In the literature, cases like this in which the diagnosis of pulmonary hydatid cyst is made by endobronchial ultrasound are not usually seen. Although many imaging modalities such as plain chest radiography, cross-sectional imaging (MDCT and MRI), echocardiography and conventional pulmonary angiography have been used in the diagnostic approach, we recommend endobronchial ultrasound for the differential diagnosis of cases with cystic formation.