This paper reports six cases (age range 8 months to 69 years) of iatrogenic foreign bodies lodged within the heart or great vessels. Four cases were produced during left heart catheterization by breakage of a metal stylet, and two after the insertion of a Pudenz valve (for hydrocephalus) which embolized into the right ventricle and pulmonary artery.In five of these patients, the foreign body was intracardiac (three in the left ventricle and two in the right ventricle and pulmonary artery) and the open-heart surgery was utilized for successful removal. In the sixth patient, the stylet was removed from the innominate artery via a closed procedure. Five of the six patients survived (including the youngest and oldest) and their postoperative course was uneventful. The one death followed removal of the right-left atrial foreign body and total aortic valve replacement for calcific stenosis, and failure appeared related to the basic disease rather than to the foreign body.Such complications have rarely been reported in the literature. The high ratio of success, if treatment is prompt before the formation of clots (which is rapid), needs full appreciation, and emphasis is given to the benefits of prompt surgery for removal.