The objective of the paper was to assess the correlation of mechanical properties of the selected legume seeds on their weight and thickness. The following were studied: seeds of narrow-leafed lupine Bojar and Regent, yellow lupine Mister and Taper, horse beans Amulet and Granit, and soya Aldana. The mechanical properties of seeds determined under quasi-static loads. Single seeds were loaded in a direction perpendicular to the plane of division of the cotyledon with a constant velocity of v=10 mm∙min ^-1. The tested cultivars of legume differed significantly with vulnerability of their seeds. Only relative deformation and relation of destructing force work to the seeds weight similarly differentiated the tested cultivars among the analysed strength parameters. The tested legume varieties had significantly different mechanical properties. Cultivars of the tested legumes, whose seeds have greater weight and thickness, were less susceptible to mechanical damage. In all varieties of seeds, the weight increase resulted in the increase of their resistance to damage, whereas the increase in the thickness of seeds clearly influenced only the reduction of deformation and ratio of destructive force and mass.