In order to study the inheritance and nature of action of the genes controlling various traits in maize, K18 х K74/1 and K18 х K3653/5 were crossed. Parents with F1, F2 and backcrosses generations were planted in a randomized complete block design with three replications in 2005. The results obtained from the analysis of variance showed significant differences between studied generations for all traits. Thus, the generation mean analysis was performed for all traits. The results showed that although, additive, dominance and effects of epistasis were important for days to silking, days to physiologic maturity, days from silking to physiologic maturity, ear height and the number of kernels per row and most of traits in K18 х K74/1 and K18 х K3653/5 crosses respectively but the dominance gene effects were the most important for inheritance of the majority of traits. The F1 means of most traits in both crosses were more than parents, which indicate heterosis. Average broadsense heritabilities were between 29% and 69% and between 45% and 81% and the range of narrowsense heritability were between 0.9% and 60% and between 0% and 51% for all traits In K18 х K74/1 and K18 х K3653/5 crosses, respectively.