The suitability of wheat grains for milling varies widely according to a large number of factors, Among these factors, kernel hardness and vitreousness contribute to a considerable extent to the milling behaviour of wheats, yield of mill streams and flour size distribution. An original method has been developed to measure the rheological properties of cereal grain endosperm. The failure stress depends on both hardness and vitreousness of endosperm whereas Young's modulus appears to be related above all to hardness. In addition, depending on the kernel texture, the mode of fracture of the grain may be either fragile or ductile. The results of these rheological measurements appear to be in good agreement with the milling behaviour: of the grains.