Abstract: Objective To investigate the safety and effectiveness of left internal mammary artery. Methods One hundredand and eighty-one patients(male 119, female 62 cases) had the left internal mammary artery angiography by transradial approach with coronary angiography catheter 6F JL3. 5. Results One hundred and seventy patients completed the left internal mammary artery angiography, The total success rate was 94.0%. The left internal mammary artery angiography (ailed mainly due to tortuous aortic arch(7 cases, 6 were male and 1 female; accounted for 4% ) ; radial artery spasm(4 cases, 1 male and 3 females; accounted for 2% ). 2.2% patients had postoperative swelling and hematoma of the left arm. 3. 9% swelling and hematoma also occurred in left forearm proximal to the puncture point at the elbow. 2.8% red skin around the puncture point of herpes was also recorded. There were not other complication such as the right radial artery occlusion, arteriovenous fistula, false aneurysm, infection and ulceration of skin puncture mouth forearm compartment syndrome. Conclusion The left internal mammary artery by transradial approach with coronary angiography catheter is a safe, effective and readily acceptable method.