Atrial septal defect (ASD) repairs have successfully been performed on the arrested heart with the da Vinci S Surgical System (Intuitive Surgical). This study assessed the feasibility, safety, and efficacy of the use of the da Vinci S Surgical System for on-pump ASD repairs on the beating heart without cross-clamping the aorta.This prospective study included 24 consecutive patients who underwent ASD repair surgery between June 2008 and June 2009. All of the procedures were completed with the da Vinci S robot via 3 port incisions in the right chest and a 1.5-cm working port. The operations were carried out on the beating heart with mild hypothermic cardiopulmonary bypass (CPB) without cross-clamping the aorta. Venting the heart from the working port provided adequate visualization of the operative field.All patients underwent complete repairs. Fourteen patients underwent ASD closure with a fresh autogenous pericardial patch, and 10 patients underwent direct ASD closure. Concomitant surgery was required in 4 patients. The mean (+/-SEM) CPB time was 65.6 +/- 17.7 minutes, and the mean operative time was 98.5 +/- 19.3 minutes. No patient required transfusion of red blood cells. The length of patient stay in the intensive care unit was 0.5 to 1.0 days. The length of hospital stay was 4 to 5 days. Follow-up transthoracic echocardiography evaluations showed no residual atrial septal leakage. There were no operative deaths, strokes, or other complications. All of the patients were discharged.We have shown that use of the da Vinci S Surgical System to perform on-pump ASD repairs on the beating heart without cross-clamping the aorta is feasible, safe, and effective.