We have described a child with pseudoaneurysm of the thoracic aorta caused by an ingested safety pin, who survived this life-threatening injury in which the diagnosis was elusive for four months. Esophageal foreign bodies, especially sharp, pointed ones, can cause such a cardiovascular complication. A high index of suspicion is imperative if the diagnosis is to be made early. Serial chest x-ray films showing an enlarging mediastinal mass should trigger aggressive radiologic evaluation.