OBJECTIVE Sinus venosus type atrial septal defects (SVASD) differ from the secundum atrial septal defects by its location and high incidence of combination with other cardiac anomalies, which inherently increases the risk of postoperative complications. Right atriotomy is the most preferred approach for repairing the SVASD. Postoperative sinus node dysfunction or other rhythm disturbances can be observed. We compared the postoperative complications between lateral cavatomy and right atriotomy in patients who had SVASD. METHODS Twenty-seven patients who had SVASD (of 384 total ASDs) associated with partial anomalous pulmonary venous connection (PAPVC) underwent surgical repair during the period of January 1992 - December 2001 in Gülhane Military Medical Academy. Sinus venosus type atrial septal defect was repaired through right atrial incision by routine bi-caval cannulation in 14 patients (Group 1) and repaired through lateral caval incision by direct caval cannulation in 13 patients (Group 2). Lateral cavatomy was closed by pericardial patch in Group 2. We analyzed the relationship between incidence of rhythm disturbances and the technique in patients who had SVASD with or without partial anomalous pulmonary venous connection prospectively. RESULTS All patients had a classical superior SVASD intraoperatively. Persistent left superior vena cava (PLSVC) was observed in 5 patients (Group 1=3 patients, Group 2=2 patients). Postoperative mortality was seen in one patient in Group 1 due to pulmonary venous obstruction. In Group 1, one patient underwent re-operation for upper and middle lobectomy of the right lung. Ambulatory Holter monitorizations were done in all patients per 3 months periodically. In Group 1 sinus node dysfunction was observed in 4 patients and atrial fibrillation was observed in 2 patients, while in Group 2 only one patient had atrial fibrillation during follow-up period (p=0.037). CONCLUSION Repair of SVASD in adult patients is associated with low operative mortality and morbidity. The closure of the defect by pericardial patch is the most preferred technique but obstruction of caval veins can be seen. We suggest that posterior cavatomy can be preferred to atriotomy because of low incidence of sinus node dysfunction and pulmonary or caval obstruction.