In agricultural machines, seeds are injured, which damages the crop: conditions are created for the development of harmful organisms during storage, field germination decreases. The relevance of the study of seed injury is caused by the need to improve technologies and designs of agricultural machines that reduce or eliminate seed damage. Currently, there are no studies to assess the change in the amount of grain injury over the entire production cycle. The purpose of this work is to establish the regularity of changes in grain injury in agricultural machines by stages of technology. On the basis of a specially developed end-to-end technique, the injury of wheat seeds of different varieties, differing in categories according to GOST R 52325-2005 “Varietal and sowing qualities of seeds of grain and leguminous plants” and their reproductive anatomical parts - endosperm, embryo, tuft, was experimentally investigated. A new concept of “degree of injury” is introduced and a formula for its calculation is proposed, which allows quantifying the amount of injury to grain seeds and their anatomical parts. It was revealed that the greatest injury occurs in combine harvesters, where the degree of injury is 36.1 ...44.2%. It is established that at each stage, regardless of the technology used, the complex of machines and equipment, the number of injured seeds increases: during post-harvest processing, taking into account the separation of part of the injured grains, which cannot be tracked by 0.1 ...3.3%; when removing from storage and final processing of seed material before etching by 5.0... 10.4%; in a etching machine with screw loading and unloading devices by 7.3 %; in a screw-type seed loader by 4.9%; in seeding machines of individual dosing and gravity feeding of seeds into coulters by 2.9...3.2%, and group dosing with pneumatic transport of the sown material by 4.4...4.7%. In the end, when entering the soil, the degree of injury to wheat seeds is in the range of 57.0 ... 61.4%. Of these, with injury to the endosperm – 51.7...58.4%, germ – 1.9...2.2%, tuft – 1.1…1.8%. The lowest values were obtained when using bags for loading sowing machines, instead of a screw loader of seeders.