Pulmonary artery aneurysm is a rare abnormality in the cardiovascular system. Electroconvulsive therapy triggers a release of catecholamines, causing a marked and usually transient tachycardia and hypertension, which could increase the risk of aneurysmal rupture. We report a case of a 56-year-old woman with severe depression and an incidental finding of a large left pulmonary artery aneurysm who received 16 treatments of electroconvulsive therapy without adverse effect.