Computed tomography (CT) slices are combined with computational fluid dynamics (CFD) to simulate the flow patterns in a human left coronary artery. The vascular model was reconstructed from CT slices scanned from a healthy volunteer in vivo. The spatial resolution of the slices is 0.6 x 0.6 x 0.625 mm so that geometrical details of the local wall surface of the vessel could be considered in the CFD modeling. This level of resolution is needed to investigate the wall shear stress (WSS) distribution, a factor generally recognized as a related to the atherogenesis. The WSS distributions on the main trunk and bifurcation of the left coronary artery of the model in one cardiac cycle are presented, and the results demonstrate that low and oscillating WSS is correlative with clinical observations of the atherosclerotic-prone sites in the left coronary artery.