In this work the estimation of changes in the technological hardens index was carried out for samples of three varieties of wheat grain: Kamila, Kobra and Roma. The samples were dried in a dryer using hot air and optionally microwave radiation. The hardness index monotonically decreased in proportion to the time of drying for both, the hot air and the microwave drying methods. In addition, the microwave drying caused a significant reduction in the hardness index in the whole range of the pre-set drying limes. The changes in hardness were closely associated with the amount of internal damage in single grains, originated during the drying process.