1. The first successful application of a transcatheter occlusion of patent ductus arteriosus (PDA) was performed in 1977. Since that time, with continuing continuing improvement and modification of the equipment as well as well in the implantation technique, a clinical success rate of about 84% was accomplished. In children's hospital, Seoul National University, since March 1992, 29 children with simple PDA were treated with use of the Rashkind PDA occluder systems. Successful closure was accomplished in 27 (93%) of the total cases. Postrelease embolizations occurred in 2instances with oversized large ductus(> 8mm) and they required emergency surgery. Residual shunt rate (no audiblc murmur)by color Dopplcr Echocardionraphy was 10% (3 cases) at 6 months after implantation. We conchude that transcatheter closure of patent ductus arteriosus is feasible in the majority of chidren with PDA.