Introduction: Atrial Septal Defect is the most common congenital heart disease. Minimally invasive cardiac surgery is being perfomed routinely at several cardiovascular centers in Vietnam. At E Cardiovascular Center, from 2016 to 2019, we performed total endoscopic closure for atrial septal defect in children using 4 trocars. From 2020 to present, we have reduced the number of trocars to three. This report was to evaluate the effectiveness and early results of total endoscopic closure with 3 trocars for atrial septal defect in children. Method: Twelve children underwent ASD closure from 1/2020 to 5/2021, with mean age of 7.7 years old (range from 2.5 to 11); mean weight was 20.8 kilograms (range from 12 to 40). All the patients underwent the operation with peripheral cardiopulmonary bypass (CPB). Result: The mean peripheral circulation time was 70 minutes (range from 56 to100 minutes) on beating hearts. There were 8 cases with patch-closure and 4 cases with direct-closure. After operations, we reexamined by echocardiography, the atrial septal defects were closed completely with no residual shunt, the common femoral arteries at the cannula position were normal and no stenosis were present. Conclusion: Totally endoscopic closure for ASD on beating hearts with 3 trocars is save with a very good short-term results.