In a previous study, the radial approach for coronary angiography was shown to be associated with a lower success rate and longer procedural and X-ray times compared to the femoral approach. However, this approach is associated with a steep learning curve. A series of 210 consecutive nonselected patients were randomized to femoral versus right radial approach or femoral versus left radial approach by two experienced operators. Clinical characteristics were similar in the three groups. Technical failure occurred in one patient in the right radial group with subsequent crossover to left radial artery. The number of coronary catheters used was lower in the right radial group (1.4 +/- 0.7 vs. 2.1 +/- 0.4 for the two other groups). The procedural duration was longer with left radial (14.2 +/- 3.3 min; P < 0.05) approach than with right radial (12.4 +/- 5.8 min) and femoral (11.2 +/- 3.3 min) without significant differences between femoral and right radial. X-ray exposure was shorter in the femoral group (3.1 +/- 1.7 min) than in both radial groups (right: 3.8 +/- 2.2 min; left: 4.2 +/- 1.7 min). The angiographic quality was not different between the three groups for RCA, but was less good for LCA through right radial approach. Bed rest and hospital stay were shorter in the two radial groups. The comfort was judged better with the transradial approach. An ad hoc PTCA was performed in 45.7% of femoral patients, 41.4% of right radial, and 44.3% of left radial with immediate sheath withdrawal (closure device for femoral group). There were no severe complications in the three groups, but two patients from the femoral group were discharged later because of vascular complications. The total cost of coronary angiography was higher in the femoral group. In conclusion, after the learning period, transradial coronary angiography can be performed with a high success rate, low rate of complication, and good angiographic quality. It is associated with a slight increase in procedural (LR) and fluoroscopy times, but permits earlier ambulation and discharge, improves patient comfort, and reduces the cost.