The sorption drying of seeds of three cultivars of bread winter wheat (Sadovo1, Sadovo 772 and Katia) and three cultivars of durum wheat (Progress, Vazhod and Beloslava) was carried out. The water activity (aw) was used for illustration of drying process for both wheat species. The equilibrium moisture content of the seeds was determined at different parameters of the sorption drying. The ranges of water activity (aw) were determined for achievement of maximum seed storability (s) under long-term storage conditions in the gene bank. The best storability was achieved at aw=0.297 for bread wheat and at aw=0.197 for durum wheat. The suggested levels of seed moisture were respectively 6.35-6.05% for bread wheat and 6.09-5.82% for durum wheat. At appointed seed drying levels better storability under gene bank conditions was achieved and elimination of the negative effect of free water freezing at -18oC.