Abstract: Background and Objective: Wheat bread is classified as the main food crop in Egypt. However, Egypt is the largest importer of wheat globally. The objectives of this study were to increase genetic variation of bread wheat and to identify among mutant lines those with high-yielding under marginal lands conditions. Materials and Methods: Grains of five bread wheat varieties were irradiation by three doses of gamma rays (100,200 and 300 Gy). Fifteen M0 combination seeds along with the mother varieties arranged in randomize complete blocks design with three replicates at Agricultural Production and Research Station of National Research Centre, Egypt, during four winter seasons (2016-2019). The phenotype selection was applied to the M3 generation based on a longer spike length, as a result, twenty-three mutant lines have been created, which considered as putative mutants. To confirm these mutant lines, five distinct mutant lines out 23 mutant lines were reevaluated based on grains yield components in M4 generation. Results: Analysis of variance showed significant variation (p<0.05) among resource mutant lines for quantitative phenotypic traits in mutated generations. Compared to the mother varieties, five mutant lines presented highly outstanding quantitative phenotypic traits. All characters recorded high heritability accompanied with moderate genetic advance, therefore, the possibility of improving wheat grain yield through phenotypic selection. All characters, except plant height, evidenced to be priority traits in selection for higher grain yield due to their powerful direct association with grain yield. Conclusion: These mutant lines provide exciting new valuable resources to investigate and improvement of complex traits in bread wheat.