Controversial data have been published on the amount of radiation exposure during radial coronary procedures. We hypothesized that in the current era, high-volume operators with optimal technique would not be exposed to higher radiation doses during radial procedures. A total of 297 patients undergoing cardiac catheterization (195 elective diagnostic coronary angiograms and 102 elective coronary interventions) were prospectively assigned in a random fashion to the radial access (RA) or femoral access (FA). All procedures were performed by the same operator with vast experience in radial procedures and standard measures for radiation protection were used. Operator radiation exposure was measured with an electronic radiation dosimeter attached to the breast pocket of the operator on the outside of the lead apron and estimates of the ambient dose equivalent were derived. For coronary angiograms, fluoroscopy time (2.8 +/- 2.1 vs. 1.7 +/- 1.4 min; P < 0.001) and dose-area product (15.1 +/- 8.4 vs. 13.1 +/- 8.5 Gy x cm(2); P < 0.05) were increased by 18% and 15%, respectively, for RA vs. FA. Operator radiation exposure was 100% higher for the RA compared to the FA (64 +/- 55 vs. 32 +/- 39 microSv; P < 0.001). For coronary interventions, fluoroscopy time (11.4 +/- 8.4 vs. 10.4 +/- 6.8 min; P = NS) and dose-area product (46.3 +/- 28.7 vs. 51.0 +/- 29.4 Gy x cm(2); P = NS) for RA and FA were not statistically different. However, operator radiation exposure was increased by 51% for the RA compared to the FA (166 +/- 188 vs. 110 +/- 115 microSv; P < 0.05). This study demonstrates that the radial approach is burdened with a 100% increase in operator radiation exposure during diagnostic coronary catheterization procedures and a 50% increase during coronary interventions, provided that no special devices for radiation protection are used. Measurements of radiation dose, such as fluoroscopy time and dose-area product, substantially underestimate the disproportionate rise in radiation exposure. Special precautions are warranted to improve radiation protection during invasive coronary procedures via the radial approach.