Several wheat genotypes were screened against heat stress. Seven wheat (Triticum aestivum L.) cultivars obtained after screening against heat classified as tolerant, moderately tolerant, and susceptible to heat stress, were mated in a complete diallel mating system to study the inheritance pattern of relative cell injury percentage (cell injury %) and some yield contributing parameters under normal and heat stress conditions. Significant genotypic differences were found (P < 0.01) for all the studied traits under both regimes. The scaling test disclosed partial adequacy for traits such as days to heading and days to maturity, but for flag leaf area and relative cell injury %, it showed full sufficiency under both environments. The model for grain yield per plant and biomass per plant were fully adequate under normal conditions, but partially adequate under stress. The harvest index showed partial adequacy under normal conditions, but was fully adequate under stress. The additive component of genotypic variation (D) was significant for all studied traits and more significant than the H1 and H2 dominance components. Values of the gene proportion with positive and negative effects in the parents (H2MH1) demonstrated an unequal distribution of dominant genes in the parents for almost all the traits except for flag leaf area, grain yield per plant, and harvest index which showed an equal distribution of dominant genes under stress conditions. High heritability estimates were found for days to heading, days to maturity, flag leaf area, grain yield, and relative cell injury percentage under both regimes. Moderately high estimates were found for biomass per plant and harvest index.