Aneurysms involving the main pulmonary artery and its branches are rare. Clinical experience is limited, and their management is not well established. We present the case of a 35-year-old male patient with dyspnea and hemoptysis in whom subsequent imaging studies revealed a giant pulmonary artery aneurysm associated with an uncorrected patent ductus arteriosus and Eisenmenger's syndrome. We chose to treat the patient conservatively with medical management due to the development of Eisenmenger's physiology while waiting for heart-lung transplantation.