Objective: To evaluate the difference between the right and left radial approach in performing the trans-radial coronary intervention Method: From Jan. 2003 to Dec. 2004, we performed transradial percutaneous coronary interventions in 711 cases with the left approach (Lt group) and in 614 cases with the right approach (Rt group) in patients with a normal Allen���s test of both arm. We compared the procedural success rate, crossover rate, puncture time, total procedural duration, fluoroscopy time, the amount of contrast material used and local vascular complication between the two groups. Results: Baseline clinical and angiographic profiles were comparable in both groups. The puncture time, the amount of contrast material used, selection of guide catheter and local vascular complication were similar between the two groups. The success rate via radial access was similar both groups (Rt group; 91.9% vs. Lt group; 93.5%, p=0.056) However, crossover rate was lower in the Lt group than Rt group (2.7 % vs. 4.6%; P=0.04). Total procedural time (32.3 짹 25.4.4 vs. 30.7 짹 17.6 min; P = 0.03) and fluoroscopy time (16.9 짹 12.6 vs. 13.9 짹 7.9 min; p=0.01) were shorter in the Lt group. Number of guide catheter usage was higher in the Rt than Lt group (1.21짹0.48 vs. 1.08짹0.33; p=0.04) Conclusion: Left radial approach may provide increased procedural efficacy for transradial PCI compared to the right radial approach.