Abstract: Fifteen inbred lines and three testers of maize were crossed in line x tester scheme to study the combining ability effects for earliness, grain yield and yield components. A yield trial included the 45 top crosses, 15 inbred lines, 3 testers and two check hybrids S.C. Pioneer 3084 and T.W.C Giza 352. The experiment was conducted for three years at the Agricultural Research Station of the Faculty of Agriculture, Moshtohor, Benha University. The experimental design was randomized complete blocks with three replications. Mean squares due to crosses (C) inbred lines (L), testers (T) and line x tester (LxT) were significant for most studied traits for the combined analysis over two evaluation seasons. Significance of interaction variance for C, L, T and LxT with seasons on most studied traits was detected. δ2SCA played the major role in determining inheritance of all traits, revealing that the largest part of the total genetic variability associated with these traits was a result of non- additive gene action. The magnitude of the interaction of δ2SCAxyears (SY) was generally higher than for δ2GCA x SY. This indicates that non-additive type of gene action is more affected by SY than additive and additive x additive types of gene action. Inbred lines M L4, 8, 9, 10, 11 and L12 were reliable general combiners for earliness and M L3, 4, 5, 6 and L13 for grain yield plant-1. For earliness the top-cross M 212D x SC (M 201xM 204) gave the best Sij effects. Regarding grain yield plant-1, five SC between M L 204 and each of inbred lines M 232A, M 202C, M 242A, M 212D and M 236B as well as the two TWC M 202cxSC (201x204) and M 236BxSC (201x204) showed significantly and out yielded than check hybrid SC Pioneer 3084 by 18.99%, 12.67%, 15.71%, 11.29%, 14.11%, 10.55% and 6.56% in the combined analysis, respectively.