Background. Totally thoracoscopic cardiac surgery is an alternative to traditional cardiac surgery in adults, and in few cases, in small children. This study assesses totally thoracoscopic cardiac surgery and its advantages for application to small children with low body weight. Methods. From March 2009 to October 2010, 28 patients, with a mean age of 5.8 +/- 2.1 years and mean weight of 15.0 +/- 4.65 kg (range, 13.5 to 22 kg), underwent totally thoracoscopic atrial septal defect closure. Three incisions 1.0 cm to 2.5 cm in length were made on the chest wall. Direct sutures were made in 20 patients, whereas Dacron patches were used in 8 patients. Mean follow-up was 6 months (range, 0 to 24 months). Results. Cardiopulmonary bypass time was 56 to 126 minutes, and the aortic cross-clamp time was 36 to 65 minutes. A total of 28 cases were classified as New York Heart Association functional class I. No patient required further operation. Conclusions. Totally thoracoscopic surgical atrial septal defect closure in small children is feasible, minimally invasive, safe, and has good cosmesis. (Ann Thorac Surg 2011;92:200-3) (C) 2011 by The Society of Thoracic Surgeons