An analysis of internal damage increase was performed for samples of winter and spring wheat (three varieties of each), for damage caused by dynamic loading (two levels: 20 m/s and 25 m/s). The internal damage increase was determined separately for every kernel, on the basis of its damage status before and after loading. The internal damage status (endosperm cracks) was assessed by means of a damage index calculated on the basis of results of damage identification within the fields of a square grid superimposed on the X-ray image of a kernel analysed. Increase in the mean damage index for a grain sample was adopted as a measure of the vulnerability of the grain sample to damage caused by the load applied. Quantitative and qualitative analyses were performed for the status of damage of the grain samples of the varieties under study. Especially interesting conclusions were formulated analysing the 'damage balance' of the grain samples. The methods used in the study can be applied also in other laboratory studies on damage to cereal grain or to the seeds of certain crop plants, e.g., when studying the effects of the successive stages of their destruction.