AbstractThe radiographic anatomy of the IMAs is described based on bilateral selective arteriography in 100 patients with coronary artery disease. The right and left IMAs were identical in caliber in their mid portions in 94% of cases. Fifteen percent of the IMAs measured less than 2 mm in luminal diameter at the level of the fourth costal cartilage. The side branches showed a great deal of variability and asymmetry in their origin and distribution. The understanding of the radiographic anatomy of the IMA and its branches is helpful in preoperative appraisal and is crucial for postoperative evaluation of the IMA grafts.