BACKGROUND: Right brachial access in diagnostic coronary arteriography (CAG) has demonstrated advantages over femoral approaches, including earlier ambulation and more predictable hemostasis, particularly when small diameter catheters were used. Poor results from some earlier reports of brachial CAG have been due partially to the need to use large diameter catheters for positional control. Technical advances in catheters and contrast injection may increase the utility of brachial access CAG. PURPOSE AND STUDY DESIGN: We evaluated three 4 French (Fr) catheters with new shapes and with a large internal to external diameter ratio that were designed to overcome previous limitations to brachial CAG. Contrast agent was delivered with a novel power injector (CAG-20) intended for arteriography using small catheters. Routine right brachial access CAG and left ventriculography (LVG) were evaluated in 2663 (69%) of 3880 consecutive patients admitted for examination from 1991 to 1995. The study population included 128 patients (5%) with left main trunk disease, 819 (21%) with old myocardial infarctions and 1747 (66%) with more than one vessel disease. For this trial, 1217 patients with valvular disease, ischemia associated with aortic or peripheral vascular disease, congenital cardiac disease and post-surgical and emergency catheterization were excluded because femoral access or a larger catheter (> 4 Fr) were required in those cases. RESULTS: A total of 2573 (97%) diagnostic quality CAG (> grade 3/5) were obtained solely with 4 Fr catheters placed via the right brachial artery. Of the other 66 examinations, 50 were completed through the brachial route but with alternate size or shape catheters and 16 cases required the femoral JudkinÕs technique. Useful LVG (> grade 2/4) were obtained from 2604 patients (98%). Overall, 2536 (95%) of cases provided clinically valuable images for both CAG and LVG from brachial access. We experienced one semi-emergency bypass operation and one emergency stent implantation caused by coronary dissection. There were no deaths, acute myocardial infarctions, loss of pulse or nerve injuries. CONCLUSION: Power-injector assisted, brachial 4 Fr CAG and LVG proved to be safe and cost-effective. Brachial access has the potential to become a routine method for out-patient cardiac opacification.