This experiment was conducted at the field of Field Crop Dept. College of Agric / Univ.of Baghdad,to evaluate the genetic gene effects to some traits of maize. Six generations P1, P2, F1, F2, BC1 and BC2 for four crosses produced from crossing of genetically different six inbred lines. The six parameters were evaluated in randomized complete block design with four replications. The analysis of variance showed significant differences among generations. Means of F1′s were higher than the highest parent for all the traits of all crosses, indicated over dominance gene action. Hybrid vigor and heterosis were positive for most of traits for crosses. Result of scaling test for four criteria A , B, C, and D indicated significant effects of non-allelic interaction controlling genetic variation among six generations for seven traits. The mean effects were highly significant for all traits in all crosses indicated that all traits were quantitatively inherited, also indicated that lines had genetic diversity. Dominance effects were higher than mean and additive effects for all traits and all crosses, indicated the importance role of dominance component of gene action in inheritance traits. There were different type of epistasis interaction effects observed for various traits and crosses. Their values were varied for different trait and crosses. The dominance × dominance interactions were higher than other epistasis interaction effects.We can conclude that the traits in all crosses shown the complex behavior, hence the selection should be delayed after several generations of segregation until reached homoztgosity.