Standard coronary angioplasty balloons have generally not been available in diameters exceeding 4 mm. Consequently angioplasty of larger arteries and grafts is commonly performed with undersized balloons. "Hugging balloon" techniques and the use of peripheral angioplasty balloons introduced without a guiding catheter have been advocated. We utilized oversized (4.5--6.0-mm diameter) modified angioplasty balloons to perform angioplasty in 20 patients with large coronary arteries and saphenous vein grafts. Oversize balloons were used in conjunction with otherwise standard coronary angioplasty equipment and intracoronary stents.