A half diallel cross was performed between six bread wheat (Triticum aestivum L.) genotypes, Line Yr5, Shandwell 1, Gemmeiza 11, Misr 4, Sakha 95, and Sids 14 during the 2022/2023 winter season. The resulting 15 F1 crosses were evaluated during the 2023/2024 season under normal irrigation and drought stress conditions using strip plot design in RCB arrangement with 3 replications at Khattara Research Station, Sharqia, Egypt, to calculate mean performance, drought stress tolerance measurements, effects of general and specific combining abilities, mode of gene action, and heritability. Results were taken on number of days to heading, number of days to maturity, plant height, chlorophyll content, number of spikes plant-1, number of grains spike-1, weight of thousand grain, and grain yield plant-1. Results cleared that mean squares due to genotypes, parents, and crosses, and parents vs. crosses were highly significant for most studied characters under both conditions. Moreover, general and specific combining abilities mean squares were highly significant for most studied characters under two conditions. Wheat genotype Line Yr5, as well as the F1 crosses (Line Yr5 x Shandwell 1), (Line Yr5 x Misr 4), and (Gemmeiza 11 x Sakha 95), exhibited the lowest reduction ratio (R%), tolerance index (TOL), and drought sensitivity index (SSI) values for grain yield-1. Hence, these genotypes exhibited greater tolerance to drought stress compared to others. The additive genetic component (D) was greater than the dominance component (H1 and H2) for number of days to heading, number of days to maturity, and plant height under normal irrigation, resulting in (H1/D)0.5 being less than unity. Nonetheless, the dominance genetic component was more than the corresponding additive one for total chlorophyll content, number of spikes plant-1, number of grains spike-1, weight of thousand grain and grain yield plant-1 under the two conditions as well as number of days to heading, number of days to maturity and plant height under drought stress condition, resulting in average degree of dominance (H1 /D)0.5 was more than unity. The highest heritability in the narrow sense (Tn) was observed for number of days to heading, number of days to maturity, and plant height under both conditions. Additionally, under normal irrigation conditions, heritability was also high for the number of spikes plant-1, weight of thousand grains, and the number of grains spike-1. On the other hand, chlorophyll content showed moderate heritability under specific conditions, including grain yield plant-1 and the number of spikes plant-1, along with the number of grains spike-1 and the weight of thousand grains under drought stress conditions. In contrast, the heritability for grain yield plant-1 under drought stress conditions was low.