Relations between mechanical properties, damage susceptibility and microstructure of five Polish cultivars of barley were examined. Brabender Hardness test, Instron measurements, PSI, PRI, and glassiness were used to characterise mechanical properties. The structure analysis was carried out with scanning electron microscopy and X-ray microscopy. Mechanical properties of grain were related to barley cultivar. Grain of cultivars with glassy endosperm were characterised by higher mechanical resistance than those with floury endosperm. Particle size distribution of the extracted starch granules, as determined by digital image analysis, did not correlate with the mechanical properties of barley grains. Generally speaking, the number of damaged kernels correlated with the fracture resistance and was related both to the direction of compression force and water content of grain. Compression along the axis of kernel thickness always resulted in a high number of damaged creases. When water content was high no damaged to the crease zone and a low number of internal damage was characteristic of kernels compressed along the width axis. It was observed that barley endosperm cracked inside cells, while the spaces between cell walls remained unfractured.