To determine the inheritance of bread making quality of bread wheat by diallel crossing, the F1 seeds of a 5 × 5 half diallel along with their parents were grown in water-stress and non-stress conditions, in a randomized complete blocks design, at Islamic Azad University, Ardabil, Iran, in 2009, and 8 characters related to their bread quality along with 1000-seed weight and hectolitre mass were evaluated. The result of combined analysis of variance showed that the effect of stress on protein content, SDS sedimentation volume, wet gluten content, 1000-seed weight and hectolitre mass was significant . The interaction effect of genotype and stress was significant (P<0.01) for the loaf volume and hectolitre mass, and this showed different reactions of the genotypes in the stress and non-stress conditions. Also, the effects of genotype were significant for all the traits except for Zeleny sedimentation volume, grain moisture content and wet gluten content. This shows that the conditions are suitable for diallel analysis and separation of sum of squares of traits. Significance of general combining ability for loaf volume, grain hardness, moisture absorption percentage, SDS sedimentation volume, 1000-seed weight and hectolitre mass shows presence of additive effect and specific combining ability for 1000-seed weight and hectolitre mass shows non-additive gene effects in the control of these traits.