The relationship between total soluble seminal root proteins induced at cold acclimation and freezing tolerance in tetraploid wild wheat Aegilops L. (Ae. biuncialis, Ae. cylindrica) and cultivated wheat Triticum turgitum L. (Firat-93, Harran-95) was investigated. Cold acclimation was performed at 0 degreesC for 7 days. Freezing tolerance was determined with survived roots after freezing treatments at -5 and/or -7 degreesC for 3, 6, 12 and 24 h. At -5 degreesC, all tetraploid genotypes showed over 60 % tolerance for 3 h. This effect was also present in wild wheat for 6 h, but was decreased in cultivated wheat to 30-35 % tolerance for 6 h. OnlyAe. biuncialis was able to show 52 % tolerance just for 3 h freezing period at -7 V. However, all the genotypes were not survived at -7 degreesC, for 6, 12 and 24 h. Cold acclimation induced greater amounts of new soluble seminal root proteins in tolerant Ae. biuncialis (29-104 kDa, pI 5.4-7.4) than in sensitive Harran-95 (29-66 kDa, pI 6.1-8.3). Synthesis and accumulation of these proteins may be related to degree of freezing tolerance of these genotypes.