Right ventricular outflow tract obstruction, or “suicide right ventricle,” rarely has been observed after single or bilateral single-lung transplantation for the treatment of Eisenmenger syndrome. We describe our experience in 2 patients with Eisenmenger syndrome in whom right ventricular outflow tract obstruction developed, in 1 after single-lung transplantation and ventricular septal defect repair and in the other after bilateral single-lung transplantation. Both patients suffered progressive deterioration and hemodynamic instability that was unresponsive to aggressive medical therapy. Diagnosis was confirmed in both patients by transesophageal echocardiography. Operative intervention was undertaken 72 and 24 hours after transplantation, and consisted of myectomy and outflow tract patching. One patient survived; the other died intraoperatively. The index of suspicion for this problem should be high during the intraoperative performance of transesophageal echocardiography, as well as during direct gradient measurement, with consideration of immediate management of severe right ventricular outflow tract obstruction at the time of transplantation.