We experienced an intraatrial baffle repair for unroofed coronary sinus syndrome in TOF. The patient was a 32-month old female, with complaints of cyanosis, exertional dyspnea and growth retardation. Physical examination showed cyanosis of lip, clubbing of finger, growth retardation and systolic murmur[0 /Gr VI] on left sternal border. With an aid of noninvasive and invasive diagnostic procedure, the patient was diagnosed as TOF combined with unroofed coronary sinus syndrome and LSVC connecting to left atrium. After patch closure of VSD, infundibulectomy and pulmonary valvotomy, the intraatrial baffle redirection of anomalous LSVC to right atrium was undertaken. The Dacron baffle was constructed along the roof of the left atrium to the plane of the atrial septum. The intraatrial septum was then reconstructed with Dacron which was sutured to residual septal tissue. After surgery, the systemic oxygen saturation was elevated to 95.5%, as compared with preoperative value 61%. The postoperative course was uneventful.