Aneurysms of the pulmonary artery are uncommon in general but have a potentially fatal prognosis. This is derived from the potential for rupture of the aneurysm from the fact that there is commonly underlying severe pulmonary hypertension. Most cases are documented in the large postmortem series. Aneurysms of the pulmonary artery can be classified as congenital or acquired. Possible symptoms include dyspnea on exertion, cough, hemoptysis, and thoracic pain. When a large aneurysm formation of the pulmonary artery is diagnosed, surgical intervention is indicated because conservative treatment of the aneurysm will undoubtedly result in rupture with fatal outcome. We report a case of 46-year old patient with a giant left pulmonary artery aneurysm associated with severe pulmonary hypertension. A Doppler echocardiogram and a computed tomographic scan showed a giant saccular aneurysm of the left pulmonary artery (12 cm in diameter) and estimated systolic right ventricular pressure of 80 mmHg.