To assess the effects of percutaneous transluminal coronary angioplasty on endothelin-1 (ET-1) release, we assessed ET-1 concentrations at different sites of the coronary circulation in patients submitted to elective procedures. ET-1 levels immediately downstream from the plaque and ET-1 aortocoronary gradient increased significantly after the procedure, which was related to mechanical wall stress in patients only receiving balloons, but not in those undergoing stent percutaneous transluminal coronary angioplasty. No changes were found in the coronary sinus; these results suggest ET-1 release from the plaque rather than an ischemia/reperfusion-related production from the distal myocardium.