Objective: The recent advent of robotically assisted surgery has enabled totally endoscopic repair of atrial septal defects and patent foramen ovale. This study investigates the feasibility and safety of totally endoscopic repair of an atrial septal defect through small incisions on the chest without robotic assistance. Methods: Forty patients (23 female patients; average age, 15.4 ± 8.7 years; age range, 6'47 years) with secundum-type ASDs were selected for this study. Cardiopulmonary bypass was achieved peripherally. Through 3-port incisions in the right chest, pericardiotomy, bicaval occlusion, atriotomy, and ASD repair were performed by a surgeon through a thoracoscopy. Results: The cardiopulmonary bypass and aortic crossclamp times were 56.2 ± 21.1 and 38.3 ± 8.6 minutes, respectively. The length of stay in the intensive care unit was 23.0 ± 4.1 hours. There were no mortalities and no major complications in this cohort. Patients were discharged from the hospital 4 to 6 days after the operation. Transesophageal echocardiographic analysis immediately after the operation and at 30 days showed complete closure of the defect without residual shunt. Conclusions: Totally endoscopic atrial septal defect repair can be achieved without a robotically assisted surgical system. This technique is safe and effective and can be used as a therapeutic option for ASD.