This work analyses changes in internal structure of wheat groin of the three varieties: Kamila, Kobra and Roma. The samples were dried in a dryer using hot air and optionally microwave radiation. The state of internal damage in single groins was determined using the damage index (IS). obtained using the computer program "ZIARNA" which automatically analysed the X-ray images of the grains. For the two methods of drying (with and without microwave) the linear increase of damage index was observed, proportional to the time of drying The rate of change of the damage index as a result of the two methods of drying was similar. However, in the case when the microwave drying was applied average values of index IS were significantly higher than those calculated for the case when no microwave radiation was applied. An additional effect of microwave assisted drying was the fact that the differences between the state of damage of the three wheat varieties effaced, while the same differences were statistically significant if the grain was dried without microwave radiation.