The efficacy and safety of the transcatheter patch (TP) correction of a secundum atrial septal defect (ASD) was studied acutely and on short-term follow-up in 20 patients, successfully implanted with the device. TPs are made of polyurethane foam and require temporary balloon catheter immobilization on the atrial septum for 48 hours. Eighteen patients were not suitable for disk-device repair. The patient median age and ASD diameter were 37 years and 26 mm, respectively. Eighteen patients had immediate effective ASD occlusion; 2 patients had significant residual shunts. Premature leaks of the supportive balloons were responsible for the residual shunts. One of the patients with residual shunt received a second patch 6 months later with full occlusion. All patients with implants were doing well up to 24 months after implantation. Existing symptoms improved although residual shunts remained; septal anatomy was normalized, with the patched area becoming progressively indistinguishable from the rest of the septum. In conclusion, TP occlusion of secundum ASD is feasible and effective even for defects unsuitable for disk-device repair. The method appears safe acutely and on short-term follow-up, with symptomatic improvement and normalization of septal anatomy.