The present study was carried out at Shandaweel Agric., Res., Station, ARC, Egypt, in 2014/2015, 2015/2016 and 2016/2017 seasons. The present investigation aimed to determine genetic parameters and type of gene action controlling some agronomic traits of the two bread wheat crosses, Shandawel 1×   Gemmeiza 11 and Misr 1×  Giza 168 under normal 20^th Nov. and heat stress 20^th Dec. conditions, using six populations model (P₁, P₂, F₁, F₂, B_C1 and B_C2). Scaling test indicated the presence of non-allelic interactions for all studied traits except number of spikes/plant in cross 2 under normal conditions, number of grains/spike in cross1 under favorable conditions and in cross 2 under heat stress and grain yield/plant in cross 1 under normal conditions. The relative importance of additive and  dominance effects varied for traits and crosses under normal and heat stress conditions. Dominance effects were generally greater than additive, except for days to heading in cross 2 under heat stress, plant height under normal conditions in cross 2 and biological yield in cross 1 under heat stress and in cross 2 under normal conditions, indicating that dominant genes playing major role in inheritance of these beside the additive one. Dominance × dominance gene interaction was higher in magnitude than additive × additive and additive × dominance in most traits, indicating that these traits greatly affected by dominance and non-allelic interactions. Therefore, it is advisable to delay selection to later generations with increased homozygosity. Positive highly significant heterosis over better parent values were observed for all studied traits, except for plant height in cross 2 under both sowing dates, number of grains/spike in cross 1 under heat stress and in cross 2 under both environments. Broad sense and narrow sense heritability and genetic advance ranged from moderate to high in most cases. Based on these results, these two crosses could be selected to produce high yielding lines under heat stress conditions.