Vein graft stenosis is a well-recognized complication of infrainguinal bypass surgery. Balloon angioplasty is an accepted method for managing vein graft stenosis in selected patients. This intervention is not without complication. We present 2 cases of delayed pseudoaneurysm formation after balloon angioplasty of vein graft stenoses. Both cases showed a persistent contrast stain or blush as an indication of vein wall damage and propose that this is a radiological harbinger of delayed rupture and pseudoaneurysm formation.