The bend deformation characteristics of WC–Co cemented carbides were investigated in the temperature range from room temperature to 1273 K by measuring load-deflection curves and examining the structural change due to deformation, in relation to cobalt content, tungsten carbide particle size, domain (grain) size of binder phase and carbon content. The cemented carbides were almost elastically deformed up to fracture at room temperature, but they became to be plastically deformed at high temperatures above about 873 K . The high temperature deformation, however, was not composed merely of a true plastic deformation, because stable cracks were frequently formed at high stress levels. Effects of the above factors on the deformation characteristics at temperatures below 873 K can be explained mainly from the viewpoint that the binder phase is dispersion-hardened and solid-solution hardened. However, the effects of particle size and carbon content at high temperatures tended to be reverse to those at low temperatures. This is explained by the dynamic recovery of binder phase occurring at high temperatures. The deformation at high temperatures and high stress levels was found to be suppressed with increase in domain size. In this paper, the relation between transverse-rupture strength and deformation characteristics was also briefly mentioned.