Inflorescence explants of two winter wheat cultivars, Triticum durum cv. Kiziltan-91 and T. aestivum cv. Bezostaja-01, were used to evaluate the effects of vernalization period of donor plants, callus age and medium composition on regeneration capacity. Donor plants were grown for 7 d and they were exposed to 4 degrees C for 1, 2, 3, 4, and 5 weeks. The maximum inflorescence formation was observed as 79 % at 4 weeks and 73 % at 5 weeks of vernalization period for Kiziltan-91 and Bezostaja-01, respectively. Among 6 different callus induction and regeneration mediums, I-1-R-1 and I-3-R-3 have to be the best responding mediums for Kiziltan-91 and Bezostaja-01, respectively. In Kiziltan-91, calli induced from donor plants, vernalized for 3 weeks, showed a significantly lower regeneration capacity than counterparts vernalized for 4 and 5 weeks. The highest regeneration capacity of 69 % was obtained from 6-week-old calli produced from 4 weeks vernalized Kiziltan-91 donor plants. In contrast to Kiziltan-91 cultures, the effects of vernalization period and callus age on regeneration capacity were not significant in Bezostaja-01 cultures. The maximum numbers of tillers were obtained from 6-and 15-week-old calli for Bezostaja-01 and Kizilitan-91, respectively. In contrast to vernalization period of donor plants, callus age had no effect on seed number.