Less than 200 cases of main pulmonary artery aneurysms have been reported and most came from autopsy series. The aneurysms may be associated with congenital cardiovascular lesions, syphilis, degenerative changes in the arterial wall and possibly trauma. Pulmonary artery aneurysm is a true entity which can occur with or without typical clinical findings. Physicians should pay more attention to the so-called "aneurysmal dilatation" or "idiopathic dilatation" of the pulmonary artery and obtain a correct diagnosis by angiography. Since pulmonary artery aneurysm carries a risk of rupturing, the operation should be considered as soon as the lesion is recognized. Few surgical interventions have been reported.