Large sized coronary artery fistulas are rare and diagnosed in only 0.05% of adult catheterized patients. Only a minority of these fistulas are operated upon. We describe a percutaneous technique to close a left coronary artery fistula draining into the right atrium in a 30-yr-old male patient. The fistula was closed by implantation of a trefoil coil, inserted through a catheter selectively advanced into the fistula.