The purpose of the thesis was to see the influence of different temperature treatments on the reduction of hard seed percentage in three alfalfa varieties (Osjecka 10, Osjecka 88 and Slavonka). There were five different treatments: A-control treatment; B-5 days plus 7 degrees C; C-5 hours plus 40 degress C; D-1 hour plus 80 degrees C; E-2 times 2 hours -80 degrees C and two hours at plus 22-23 degress C in between. The treatments D and E were very uniform and efficient, they reduced the percentage in comparison with the control by 71-91 per cent. In treatment D, 25 times more dead seeds and 5 times more abnormal seedlings were found, if compared to treatment E, and germination energy had very low values. Treatment E only had positive effects that were reflected in the highest values for germinative energy and germination. Treatment C did not influence hard seed percentage while the treatment with prechilling was ineffective.