Determine the safety and efficacy of On pump beating heart repair of Atrial Septal Defect (ASD) with regard to postoperative neurocognitive function and to determine myocardial oxygen extraction during the procedure. The prospective study included 70 consecutive patients with Secondum ASD randomly assigned to two groups Beating Heart Group (Gp1) and Arrested Heart Group (Gp2) each having 35 patients. Gp1 patients underwent beating heart ASD with normothermic bypass without cross-clamping the aorta. Gp2 patients had conventional surgery with normothermic bypass and cardioplegic arrest. All patients were evaluated preoperatively (D0) and postoperatively on 10th day (D10) and 6 months (D6mths) for neurocognitive functions. We also compared myocardial oxygen extraction and total costs incurred. On pump beating heart repair of secondum ASD without aortic cross clamp reduces cardiopulmonary bypass time min0 vs (39.4 ± 13.2 vs 58.6 ± 15.4, p = 0.000) and total cost in rupees (26733.4 ± 3117.8 ; 31357.1 ± 1748.8, p = 0.029). There was no neurologic deficit observed in any of our patients postoperatively. Preoperative and postoperative neurocognitive functions in either group did not show any significant intergroup or intragroup deterioration. Myocardial oxygen extraction in Vol%, though significantly more in Gp1 than in Gp2(10.2 ± 2.6 ; 7.9 ± 2.0, p = 0.000) was however comparable to that seen in normal healthy beating heart. There were no mortalities The technique is safe in protecting neurocognitive functions. This technique offers simple, effective, and safe alternative to cardioplegic techniques and may be safely used in majority of ASD repairs.