"nBackground: Nowadays, the treatment of choice for anatomical correction of transposition of great arteries is arterial switch but some children are not good candidates for this operation. In these cases atrial switch or Senning procedure is an accepted method, thus outcome of this procedure needs to be better delineated."n "nMethods: This prospective study included 65 patients that underwent Senning operation in Shahid Rajaee Hospital in Tehran, Iran from 2002 to 2009 and were followed-up for one year."n "nResults: The early and late mortality rates were 16.9% and 1.5%, respectively. 51.8% of early deaths were due to simple Senning procedure, 38.9% due to a Senning with the closure of ventricular septal defect, with or without the repair of pulmonary artery stenosis, 9.3% related to palliative Senning and one late death due to simple Senning. The most common arrhythmia was accelerated junctional rhythm (18.5%). 15% of cases had Senning pathway obstruction and 1.7% had baffle leaks. Regardless of the mortalities, three patients (5.7%) had significant tricuspid regurgitation. Right ventricular systolic dysfunction was found in 13.3% of the cases, primarily in Senning with ventricular septal defect closure (37.5%). One case (1.9%) had visible cyanosis and three (5.7%) had exertional dyspnea but 94.3% of cases remained in functional class I."n "nConclusion: Since the majority of deaths following Senning procedure occur during the first month, especially on the second day post-operatively, assiduity during early post-operative period is crucial. Tricuspid regurgitation or right ventricular systolic dysfunction was not detected in most patients, suggesting optimistic prognosis for these patients.