||To determine the action of vernalization and growth habit variation in cultivars of bread wheat (Triticum aestivum L.), this research was carried out in greenhouse of Agricultural and Natural Resources Research Center of South Khorasan in 2013-2014 growing seasons. The treatments consisted of 40 cultivars of wheat and 5 levels of vernalization periods (0, 15, 30, 45 and 60 days) at ambient temperature in January and conducted with randomized complete block design with two replications. Vernalization fulfillment was determined using the final leaf number method. Fitting formula was used for each genotype. Then α and β obtained from this fitting used genotypes grouped according to the severity of its response to vernalization was used (using Wards method for cluster analysis with SPSS software). The results showed that Soissons, Zare, C.86.5, Azar2, Gaspared and Gaskogen have a highest leaves with 11 leaves in no-vernalized conditions and divided into separate groups. Roshan, Pishgam, Mihan, Tabasi, Alvand, Dena, Bezostaya, and Karaj3 were intermediate in leaf product. The rest of these were in the lowest group.