Objective To compare the efficacy and safety of pig-tail catheter-assisted 6.5 F guiding catheter and 6 F guiding catheter in transradial interventional treatment of coronary artery lesions.Methods A total of 390 patients with coronary artery lesions,who received percutaneous coronary intervention(PCI)at the Xijing Hospital of Air Force Medical University of China between January 2021 and June 2022,were enrolled in this study.By using the random number table method the patients were divided into pig-tail catheter-assistance group(n=130),6.5 F sheath group(n=130)and 6 F sheath group(n=130).The success rate of the guiding catheter being inserted in place,radial artery spasm,forearm pain or discomfort,forearm hematoma,radial artery wound compression time,hemostasis success rate,postoperative radial artery diameter,resolution time of distal swelling,pseudoaneurysm,and incidence of radial artery occlusion were compared between each other among the three groups.Results The differences in the time of guiding catheter being inserted in place,radial artery wound compression time,forearm hematoma,hemostasis success rate,postoperative radial artery diameter and incidence of radial artery occlusion between each other among the three groups were not statistically significant(all P＞0.05).The differences in the intraoperative radial artery spasm and forearm pain or discomfort between 6.5 F sheath group and 6 F sheath group were not statistically significant(both P＞0.05).The degrees of radial artery spasm and forearm pain or discomfort in the pig-tail catheter-assistance group were remarkably lower than those in the 6.5 F sheath group and 6 F sheath group(both P＜0.05).Conclusion In transradial PCI,the use of 6.5 F guiding catheter carries the same safety and effectiveness as the use of 6 F guiding catheter,while the use of pig-tail catheter-assisted 6.5 F guiding catheter can improve radial artery spasm and reduce forearm pain.(J Intervent Radiol,2023,32:1174-1177)