The use of the radial artery as preferred access site for coronary diagnostics and interventions is rapidly increasing worldwide given the extensive evidence demonstrating its benefit on vascular complications and mortality, its costeffectiveness, and the increased patient satisfaction in comparison with the femoral approach. However, this approach could be complicated by radial artery occlusion (RAO), which only rarely causes hand ischemia but more commonly impede future utilization of the radial artery as an access site for catheterization or as a conduit for hemodialysis and coronary artery bypass graft. The occurrence of RAO after catheterization has been reported in ≤30% of patients, and thrombosis or intimal hyperplasia caused by the vascular damage are suggested pathophysiological mechanisms. In addition, radial artery cannulation has also been related with several nonocclusive modifications as acute wall injuries, endothelial dysfunction, and impaired vasomotion. The aim of the Rotterdam Radial Access Research (R-RADAR) study was to describe with high-resolution ultrasound structural changes in the radial artery wall at its puncture site after transradial catheterization and investigate whether these changes might predict RAO or loss of pulsation, local pain, or functional impairment of the upper extremity.