A diallel cross involving five bread wheat genotypes was evaluated to determine the genetic behaviour of yield and its components in wheat under irrigation and drought conditions in addition to drought susceptibility index. The resultant hybrids along with their parents were evaluated in two experiments. The first experiment (stress) was irrigated once, while the second experiment (normal) four times. Genotypes mean squares were significant for all studied traits in both experiments as well as drought susceptibility index the parent P3 expressed the highest desirable values for number of kernels/ spike, and grain yield/ plant in drought condition and drought susceptibility Index. The crosses P2 x P3 and P3 x PS expressed the best mean values for most traits under stress conditions and drought susceptibility index, respectively. Mean squares due to GCA and SCA were significant for aU traits except GCA for the number of kernels/ spike in stress experiment and drought susceptibility index and SCA for grain yield in normal experiment and straw yield/ plant in drought index. High GCA/ SCA ratios which exceeded the unity were detected for most traits indicating the predominance of additive and additive x additive gene action in controlling the studied traits. Parents P3 and P4 could be considered as good combines for the number of spikes/ plant, total plant weight, grain weight/ plant and straw yield/ plant under drought condition and drought susceptibility index. Parent P2 was the best combiner for most traits under normal irrigation condition. The best SCA values were detected by the cross P2 x P3 for no. of spikes/ plant, total plant weight, grain yield/ plant and straw yield/ plant under stress condition and drought susceptibility index. Cross P1 x PS gave the best SCA effects for total plant weight and straw yield/ plant under normal irrigation experiment.