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In order to study genetic diversity, heritability and relation of some important traits with grain yield in bread wheat, 20 bread wheat irrigated lines evaluated using a randomized complete block design with three replications during two cropping cycles/years. Based on combined analysis results, there were a significant difference between genotypes. Also, in all traits, coefficient of phenotypic variation was greater than coefficient of genetical variation, indicating the effect of environment on investigated traits. The significant correlation between grain yield and number of days to maturity, spikes per m2 and the grains per spike. number of days to heading and number of days to maturity had highest heritability among traits, with 87 and 69%, respectively. Results of this showed that selection of early heading or shorter no. of days to heading and early maturing or shorter number of days to maturity is recommended to breeders for selection materials favorable for terminal warm condition and water shortage, preventing grain yield reduction. Results of cluster analysis showed that genotypes are divided in six groups. Totally, six superior genotypes from the fourth cluster were selected as superior lines. Based on bi-plot analysis, genotypes 14 and 5 showed the lowest genotype × trait interaction, but genotypes 16 and 8 showed the highest genotype × trait interaction.