Forty-one diverse inbred lines of white maize were top-crossed with two ¡nbreds as Sd-7 and Sd-63 testers during the summer of 2004 at Sakha Agricultural Research Station. The resultant top-crosses (82 Fis) were divided into three groups, i.e. group I included the first 28 F1's, followed by the second 28 F1's for group 2 and finally the third group contained the remaining 26 F1s of the total number of the 82 crosses. Each group was tested in a separate experiment, designated as Exp.1, Exp.2 and Exp.3 with the two commercial hybrids S.C. Giza 10 and S.C. Giza 129 as checks in these groups. Experiments I and 2 were evaluated at Sakha and Mallawy Stations while experiment 3 was evaluated at Sakha and Sids Stations, all in 2005 growing season. The aims of this investigation were to determine the types of genetic variances controlling grain yield ard/fed. (GY), days to 50% silking (SD), plant height (PH) and ear position% (EP%) and to identify superior top-crosses (Single Crosses) and desirable inbred lines in the studied traits. Non-additive genetic effect was found to be more impôrtant than additive genetic effect in the inheritance of all studied traits at all experiments except GY ir Exp.2, SD in Exp.3 and PH ¡n the three experiments. Additive genetic variances showed significant interaction by locations than non-additive variances in the behavior of PH and EP% ¡n the three experiments except in Exp.1. While, non-additive gene action represented the major role in the interaction by locations for GY and SD except GY in Exp.1 and SD in Exp.2. Desirable and significant g effects obtained by 12, 10, 12, and 10 inbred lines toward increasing favorable alleles for SD, PH, EP% and GY out of 41 studied inbreds, respectively. Moreover, inbreds Sk-5140/40 in Exp.1, Sk 5142142 ¡n Exp.2 and Sk-6001/83 ¡n Exp.3 had good general combiners for yielding ability and earliness simultaneously, indicating that they can be used as new inbreds in future maize breeding program for improving these traits. Four top- crosses (Sd-7 x Sk-5078/26 and Sd-63 x Sk-5126/36 in Exp I and Sd-7 x Sk-6001/83 and Sd-7 x Sk 6030/90 in Exp.3) increased significantly ¡n GY (ard/fed) relative to the best checa hybrid (S.C. Giza 10). And they were not significant differences compared to S.C. Giza 10 in the other studied traits. Beside that, seven top-crosses significant out yielding from other check (S.C. Giza 129), suggesting these promising hybrids (11 top-crosses) will be beneficial and effective in improving maize production.