Trilogy of Fallot, a rare congenital heart disease, is characterized by clinical manifestation mimicking Tetralogy of Fallot. In recent years, increased clinical awareness and improved diagnostic techniques make accurate preoperative diagnosis possible. Recently we experienced 7 cases of Trilogy of Fallot, which was corrected totally under the cardiopulmonary bypass. Preoperative diagnosis was entertained by cardiac catheterization and angiocardiography. Six cases of them have secondum type of atrial septal defect, and one has patent foramen ovate. Four cases of them have pulmonary valvular stenosis, and the others have combined pulmonary stenosis. [Valvular stenosis+Infundibular stenosis] The atrial septal defect was closed by continuous silk suture. Pulmonary valvular stenosis in six cases was corrected by transarterial pulmonary valvotomy, and the other case by transventricular pulmonary valvotomy. In the three cases of combined pulmonary stenosis, the hypertrophied infundibular portion was resected after ventriculotomy. Six patients were discharged with good results, and one patient expired due to low cardiac output syndrome.[KTCS 1978;2:153-160]