The Doppler wave form along the proximal left internal thoracic artery (LITA), which is detected by the parasternal or suplaclavicular view, shows a different pattern from that of the distal side of the LITA due to the effect of blood pulsatility from the subclavian artery. We evaluated postoperative LITA function immediately after surgery with an apical approach of transthoracic pulsed Doppler echocardiography in 124 patients and compared its results with that of one month postoperative Doppler findings and graft angiogram. The LITA was effectively detected and good quality Doppler waveforms obtained in 120 (96.8%) patients. The LITA diameter was significantly enlarged in the first month after surgery compared with that of the postoperative early phase (1.99 0.31 vs. 1.71 0.72 mm, p<0.05). The diastolic peak velocity and diastolic/systolic velocity ratio (D/S) in the postoperative early phase were 0.26 0.08 m/sec. and 1.54 0.04, respectively. These results were unchanged one month postoperatively. In graft angiography, all LITAs were patent, but three types of abnormal findings around the anastomosis such as string sign, anastomotic stenosis, and distal native coronary stenosis were indicated in 6 (5.5%) patients. The Doppler study in these patients showed decreasing diastolic peak velocity and D/S of less than 1.0. LITA Doppler wave with D/S of more than 1.0 was associated with a good angiographic finding. This technique was considered not only noninvasive but also noninfective method for postoperative early graft assessment.