Aim To investigate the plaque distribution in the bifurcation site of left anterior descending coronary artery(LAD) by means of volumetric intravascular ultrasound analysis. Methods The atherosclerotic plaque volumes in LAD were measured at LAD-diagonal bifurcation site in 53 cases. According to the position of diagonal branch, the vessel was divided into 4 quadrants:the carina side of bifurcation(quadrant 1), the pericardial side(quadrant 2), the opposite side of bifurcation(quadrant 3) and the myocardial side(quadrant 4). The relative distribution of plaque(the volume percent of each quadrant plaque in total plaque) was compared in each quadrant. Eccentricity index of plaque distribution(the ratio of plaque volume in quadrant 3 to plaque volume in quadrant 1) was compared in distal and proximal bifurcation section. Results The relative volumetric plaque distribution was the largest in the quadrant 3, followed by quadrant 4 and quadrant 2, and that was the smallest in the quadrant 1. Meanwhile, relative volumetric plaque distribution in the quadrant 4 was larger than that in the quadrant 2. In addition, the degree of vascular stenosis, the length of lesion and the eccentricity index of plaque distribution in distal bifurcation section were greater than that in proximal bifurcation section. Conclusions Whatever in the distal or proximal bifurcation site of LAD, the relative plaque distribution is the largest in the opposite side of bifurcation, and the smallest in the carina side of bifurcation. Furthermore, the lesion is more serious and the plaque distribution is more asymmetric in the distal bifurcation site.