The anatomy of the radial artery has yet to be systematically studied from the perspective of using it as a route for catheter access. We prospectively performed angiography of the arteries of the upper limb to delineate the anatomic features of the radial artery as a way to determine the feasibility of using it as a route for coronary intervention. We studied 2,211 consecutive patients submitted to transradial cardiac catheterization. In all patients, an angiography of the upper limb arteries was performed before and after procedure. Radial puncture was successful in 98.9% of patients. At angiography, anatomic variations of upper limb arteries were noted in 505 patients (22.8%) and included tortuous configurations (3.8%), stenosis (1.7%), hypoplasias (7.7%), radioulnar loop (0.8%), abnormal origin of the radial artery (8.3%), and lusoria subclavian artery (0.45%). Overall procedural success by transradial approach was 97.5%. Patients with anatomic variations of radial artery had a significantly lower puncture (96.2% vs 99.7%, P < 0.0001) and procedural (93.1% vs 98.8%, P < 0.0001) success. The procedure was successfully performed by radial approach in 98.8% of patients with tortuous configurations, 91.9% of radial stenosis, 93.9% of hypoplastic radial artery, 83.3% of radioulnar loop, 96.7% of radial axillary origin, and 60% of lusoria subclavian artery setting. Anatomic variations of the radial artery are not rare. However, they do not represent an important limitation in transradial approach if they are well documented previously. (C) 2006 Wiley-Liss., Inc.