The relationship between vernalization requirement and quantitative and qualitative changes in total leaf soluble proteins were determined in one spring(cv.Kohdasht) and two winter(cvs.Sardari and Norstar) cultivars of wheat(Triticum aestivum L.) exposed to 4°C.Plants were sampled on days 2,14,21 and 35 of exposure to 4°C.The final leaf number(FLN) was determined throughout the vernalization periods(0,7,14,24,and 35 d) at 4°C.The final leaf number decreased until days 24 and 35 in Sardari and Norstar cultivars,respectively,indicating the vernalization saturation at these times.No clear changes were detected in the final leaf number of Kohdash cultivar,verifying no vernalization requirement for this spring wheat cultivar.Comparing with control,clear cold-induced 2-fold increases in proteins quantity occurred after 48 h following the 4°C-treatment in the leaves of the both winter wheat cultivars but,such response was not detected in the spring cultivar.However,the electrophoretic protein patterns showed between-cultivar and between-temperature treatment differences.With increasing exposure time to 4°C,the winter cultivars tended to produce more HMW polypeptides than the spring cultivar.Similar proteins were induced in both Sardari and Norstar winter wheat cultivars,however,the long vernalization requirement in Norstar resulted in high level and longer duration of expression of cold-induced proteins compared to Sardari with a short vernalization requirement.These observations indicate that vernalization response regulates the expression of low temperature(LT) tolerance proteins and determines the duration of expression of LT-induced proteins. The relationship between vernalization requirement and quantitative and qualitative changes in total leaf soluble proteins were determined in one spring (cv. Kohdasht) and two winter (cvs.Sardari and Norstar) cultivars of wheat (Triticum aestivum L.) exposed to 4 ° C. Plants were sampled on days 2, 14, 21 and 35 of exposure to 4 ° C. The final leaf number (FLN) was determined throughout the vernalization periods (0, 7, 14, 24, and 35 d) at 4 ° C. The final leaf number decreased until days 24 and 35 in Sardari and Norstar cultivars, respectively, indicating the vernalization saturation at these times. No clear changes were detected in the final leaf number of Kohdash cultivar, verifying no vernalization requirement for this spring wheat cultivar. Comparing with control, clear cold-induced 2-fold increases in proteins amount occurred after 48 h following the 4 ° C-treatment in the leaves of the both winter wheat cultivars but, such response was not detected in spring cultivar. Still, the electrophoretic pro tein patterns showed between-cultivar and between-temperature treatment differences. Increasing exposure time to 4 ° C, the winter cultivars tended to produce more HMW polypeptides than the spring cultivar. Similar proteins were induced in both Sardari and Norstar winter wheat cultivars, however , the long vernalization requirement in Norstar resulted in high level and longer duration of expression of cold-induced proteins compared to Sardari with a short vernalization requirement. Theses projections that that vernalization response regulates the expression of low temperature (LT) tolerance proteins and determines the duration of expression of LT-induced proteins.