Angioplasty of degenerated saphenous vein grafts is not infrequently complicated by distal embolization of atheromatous debris. We describe an uncommon case in which balloon angioplasty of an old vein graft to a second diagonal branch of the left anterior descending coronary artery was followed by distal embolization. However, the embolization occurred in a retrograde fashion distal to the anastomotic site, resulting in occlusion of the upstream first diagonal branch. The reasons for its occurrence are discussed, together with suggestions for its recognition.