AbstractSynthesizing facial images by computer graphics (CG) has attracted attention in connection with the current trends toward synthesizing virtual faces and realizing communication systems in cyberspace. In this paper, a method for representing human hair, which is known to be difficult to synthesize in computer graphics, is presented. In spite of the fact that hair is visually important in human facial imaging, it has frequently been replaced by simple curved surfaces or a part of the background. Although the methods of representing hair by mapping techniques have achieved results, such methods are inappropriate in representing motions of hair. Thus, spatial curves are used to represent hair, without using textures or polygons. In addition, hair style design is simplified by modeling hair in units of tufts, which are partially concentrated areas of hair. This paper describes the collision decisions and motion representations in this new hair style design system, the modeling of tufts, the rendering method, and the four‐branch (quadtree) method. In addition, hair design using this hair style design system and the animation of wind‐blown hair are illustrated. © 2002 Scripta Technica, Syst Comp Jpn, 33(3): 31–40, 2002