This study reviews the current method of atrial septal defect closure at our institute with a minimally invasive approach without median sternotomy. From September 1997 to August 1998, 37 patients (13 males, 24 females) with mean age 36.5 years (range 18-67 years) underwent atrial septal defect closure by right anterior thoracotomy. Femoral vessels were cannulated through a small groin incision and extracorporeal circulation was established. Venous drainage was assisted with a centrifugal pump. Aortic crossclamping was performed through the intact chest wall using a special transthoracic clamp with sliding rod design inserted through a separate tiny 3 mm incision in the right second intercostal space in the mid clavicular line. Mean duration of cardiopulmonary bypass and aortic crossclamp time was 35 +/- 14 and 23 +/- 7 minutes respectively; mean endotracheal intubation time after surgery 6.2 +/- 3 hours; mean ICU stay 10.6 +/- 2.8 hours; mean length of thoracotomy incision 7.2 +/- 1.8 cm; and, mean hospital stay 4.2 +/- 1.8 days. There was no post-operative neurological dysfunction or femoral cannulation related complication. There was no perioperative or late mortality. No residual atrial septal defect was observed by transoesophageal echocardiography in any patient. The procedure described here provides secure closure of the atrial septal defects in minimally invasive fashion with good results.