A partial diallel-cross study involving nine bread wheat cultivars was carried out to determine the inheritance pattern of grain yield and related attributes. The results obtained in this study could provide valuable information to a breeding program developing high yielding wheat varieties under a rain-fed environment. The analysis of variance revealed significant differences among genotypes for all the studied traits. In the partial diallel analysis, the additive-dominant model adequately described most of the traits. Allelic interaction was over-dominant for biological yield/plant in group 1 and group 2, while partial dominance and over-dominance effects were found for other traits from both parental groups. The increases in the magnitude for the studied traits are generally determined by dominant genetic factors. The genitor Mahon-Demias (group 2) had the largest concentration of favorable alleles for biological yield/plant, number of spikes/plant and grain yield/plant. The parents Acsad901(group 1) and Rmada (group 2) had the most recessive genes for these characteristics.