We report our initial experience in using the Amplatzer vascular plug for closure of coronary arterial fistulas. The self-expanding, cylindrical, device is made from Nitinol wire mesh, and is available from 4 to 16 millimetres in diameter. We have now used the device to close fistulas in 3 patients, aged from 3 to 14 years, who presented with ratios of pulmonary-to-systemic flow from 1.5 to 3. In 2 patients, fistulas arising from the proximal right and left coronary arteries, with maximal diameters of 9 and 10 millimetres, respectively, had their narrowest diameter, of 6 millimetres, proximal to the entrance into the right atrium via a saccular aneurysm. The third fistula, with a maximal diameter of 16 millimetres, and with its origin from the circumflex coronary artery, entered the right atrium with nearly unrestricted flow, its narrowest diameter being 8 millimetres. For interventional closure, we chose plugs twice the diameter of the narrowest segment of the fistula, thus using 2 devices of 12 millimetres and one of 16 millimetres diameter. An arteriovenous loop was established through the fistula by snaring an exchange guide wire. Using a 7 or 8 French guide catheter inserted through the femoral vein, all plugs were placed at the narrowest segment of the fistula, leading to immediate complete closure of 2 fistulas. The third patient, with a fistula of the circumflex coronary artery, who received the largest plug initially had residual flow, but the fistula was found to be completely occluded at 12 months follow-up examination. We have demonstrated, therefore, safe and effective usage of the new vascular plug for transcatheter closure of moderate- to large-sized coronary arterial fistulas. The plug offers an alternative to cardiac surgery, or occlusion using coils.