In the process of creation of crop cultivars the breeder conducts selection and testing of the most valuable genotypes, orienting the breeding programs with relation to traits that should be represented by a given cultivar, taking into account the direction of its commercial utilisation. In the course of breeding, the material is evaluated with respect to various traits (depending on the species and on the purpose of the breeding work), among which of only marginal importance are the physical properties of seeds, even though they are highly significant in the process of their harvest, transport, drying, and – ultimately – in the processing industry. As a rule, the breeder does not have at his disposal means to perform, at early stages of breeding and with relation to the end product, laboratory assessment of the physical properties of seeds, such as e.g. their resistance to mechanical damage. Hence, in descriptions of newly introduced cultivars, their user will only rarely find information pertaining to that subject. Helpful in this respect are research works in the field of agrophysics, as agrophysicists – having in their disposal suitable measurement apparatus – are able to perform accurate determinations of the physical properties of seeds, including their properties under various provoking conditions, as for instance at various gradients of their moisture content and for various durations of storage. Those results, if they are made available to the breeders, can be utilised in the process of selection and taken into account in the creation of new cultivars. This monograph is an attempt at estimation – based on literature data – of the physical properties of cereals and legumes, dividing the material studied into two groups: material evaluated prior to the registration of a cultivar (hybrids, mutants, addition lines, collection materials, lines) and material constituting the final product i.e. commercial cultivars. The authors focused mainly on reviewing published reports concerned with seed resistance to mechanical loads, also taking into account the geometric features of the seeds, their internal damage not resulting from external forces, hardness of the seeds, and the values of forces bonding the seed to the torus and those required for pod cracking in the aspect of seed shedding. Based on statistical analyses, coefficients of variation of the analysed traits are given, as well as estimation of relations among the traits as expressed by the values of the coefficient of correlation, demonstrating mutual relations between mechanical load parameters, geometric features of seeds and utility features of crop plants, determined in field experiments.