BACKGROUND AND OBJECTIVES: Recently, minimally invasive surgical (MIS) techniques including robot-assisted operations have been widely applied in cardiac surgery. The thoracoscopic technique is a favorable MIS option for patients with atrial septal defects (ASDs). Accordingly, we report the mid-term results of thoracoscopic ASD closure without robotic assistance. SUBJECTS AND METHODS: We included 66 patients who underwent thoracoscopic ASD closure between June 2006 and July 2014. Mean age was 27±9 years. The mean size of the ASD was 25.9±6.3 mm. Eleven patients (16.7%) had greater than mild tricuspid regurgitation (TR). The TR pressure gradient was 32.4±8.6 mmHg. RESULTS: Fifty-two (78.8%) patients underwent closure with a pericardial patch and 14 (21.2%) underwent direct suture closure. Concomitant procedures included tricuspid valve repair in 8 patients (12.1%), mitral valve repair in 4 patients (6.1%), and right isthmus block in 1 patient (1.5%). The mean length of the right thoracotomy incision was 4.5±0.9 cm. The mean cardiopulmonary bypass time was 159±43 minutes, and the mean aortic cross clamp time was 79±29 minutes. The mean hospital stay lasted 6.1±2.6 days. There were no early deaths. There were 2 reoperations. One was due to ASD patch detachment and the other was due to residual mitral regurgitation after concomitant mitral valve repair. However, there have been no reoperations since July 2010. There were 2 pneumothoraxes requiring chest tube re-insertion. There was one wound dehiscence in an endoscopic port. The mean follow-up duration was 33±31 months. There were no deaths, residual shunts, or reoperations during follow-up. CONCLUSION: Thoracoscopic ASD closure without robotic assistance is feasible, suggesting that this method is a reliable MIS option for patients with ASDs.