The presence of an intra-atrial patch (IAP) has been considered a relative contraindication to transseptal puncture (TSP). The purpose of this study is to determine the efficacy and safety of the TSP through baffles, conduits, pericardial patches and other prosthetic materials in the intra-atrial septum. We reviewed the records of all pediatric patients with IAP who underwent TSP at Texas Children's Hospital from November 1979 through February 1998. The review included the cardiac diagnoses, indications for TSP, technical difficulties and follow up echocardiograms specifically addressing residual atrial shunts A total of 1958 TSP were performed. Thirty-nine patients had IAP. Cardiac diagnoses in those 39 patients included D-transposition of the great arteries after Mustard (10) or Senning procedure (6), single ventricle variant post-Fontan operation (4), total anomalous venous return repair (4), atrioventricular canal repair (9) and atrial septal defect with patch repair (6). Patients' age ranged from 1-31 years (median 7 years). The duration from the time of surgical repair to TSP ranged from 0.1-21 years (median 5 years). Indications for TSP included diagnostic and therapeutic intervention for pulmonary venous obstruction (12), creation of a baffle fenestration (2), prosthetic mitral valve evaluation (1), left ventricular outflow tract evaluation (1), access the left heart for hemodynamic evaluation (23). The IAP was traversed in 38/39 patients (97.5%), followed by diagnostic or therapeutic prograde left-heart catheterization. No complications were encountered. Follow up echocardiography in 30/38 PTS demonstrated no residual shunting across the atrial septum except for two cases in which the atrial baffle had been intentionally fenestrated. Transseptal puncture through an intra-atrial patch is a safe procedure. This technique is effective in permitting diagnostic and therapeutic left heart catheterization and does not result in residual shunting through the patch.