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Selection of breeding methods for plant genetic improvement largely depends on the genetic basis of selected traits. This research was carried out in order to study the genetic parameters of phenological and morphological traits , yield and yield components of maize using generation mean analysis of inbred lines derived from crosses KE72012 (P1) × K1263 / 1 (P2) inbred lines. This study was conducted at Torough Station of Khorasan Razavi Agriculture and Natural Resources Research Center, Mashhad, Iran, during 2012. Six maize generations include BC2, BC1, F2, F1, P2 and P1 was evaluated in a randomized complete block design (RCBD) with three replications. Analysis of variance showed higher dominance gene effects than additive effects. Average dominance gene effects (H / D) ½ in all measured traits, showed complete and over dominance gene effects indicating the importance of dominance effect in studied traits. A simple additive-dominance model performed using weighted least square analysis. Results showed not it’s adequacy for traits, indicating the importance of epistatic effects in controlling genetic variations. Broad sense heritability for all measured traits in crosses KE72012 (P1) × KE1263 / 1 (P2) ranged between 0.10 to 0.88 and the range of narrow sense heritability in this cross was between 0.02 to 0.59. Estimation of number of genes controlling grain yield showed that the one to five genes are involved in KE72012 (P1) × K1263 / 1 (P2).