[en] The present study was established in the experimental farm belonging to plant Research Department, Nuclear Research Center, Inchas to study the effect of gamma ray (0.200 and 300 Gy) on means of yield and yield attributes for irradiated populations of Giza 164 and Sakha 92, varieties in comparison with untreated control, Moreover, genetic variation was studied by estimate phenotypic, genotypic, coefficient of variation, heritability and genetic advance under selection of bread wheat varieties (Giza 164 and Sakha 92). 1- In -M₁- generation: (1995-1996) on plant with morphological change (dwarfness) was identified in 300Gy dose of Giza 164 variety. Moreover, this varient was confirmed and segregated in M₂ generation into three types of segregants (dwarf-semidwarf and tall stem). 2- Results showed that mean values of yield and yield attributes of irradiated populations in M₂ of Giza 164 and Sakha 92 varieties were insignificantly increased. High magnitudes of G.C-V.%, Hb% and Gs% for number of spike/plant and number of grain/spike were obtained, however moderate magnitude was found for the weight of grains spike. The high values of heritability and genetic gains from selection for these triaits in the next generations. The correlation between grain yield and each of number of spike/plant and number of grain/spike were positive and highly significant however, it was positive and significant for weight grain/spike. Some variants with morphological changes i.e. dwarf, semidward, tall stem, earlly maturity and brown spike were selected in M₂ generations. These variants surpassed their mother varieties for one or more of yield attributes suggesting the importance of further evaluation and confirmation of this variants in the next generations