A 37-year-old woman with Noonan's syndrome underwent surgery for patent ductus arteriosus (PDA) and ventricular septal defect (VSD) with cardiomyopathy. Preoperative examination showed a small left-to-right shunt ratio (L→R) and mild pulmonary hypertension. However she had severe heart failure and repeated upper respiratory infections. The cardiomyopathy of this patient was the dilated type rather than the hypertrophic obstructive type which is usually seen in Noonan's syndrome. Postoperative cardiac functions did not improve significantly. This report discussed the operative technique, indications, and cardiac function aspects associated with Noonan's syndrome.