A method for reconstructing 3-D motion of coronary arteries from single-plane X-ray angiogram sequences on two approximately orthogonal views is proposed. 2-D motion is firstly estimated separately along vascular centerlines extracted from angiographic projection pairs. The 3-D displacement vector of each arterial skeleton point at one instant is then reconstructed by calculating the spatial coordinates of its two ends from corresponding projections. 3-D configuration and dynamics of arteries are finally characterized. The effectiveness of the algorithm has been demonstrated on vascular phantom images and clinical angiograms and results are encouraqing.