This study was carried out at two locations (Gemmeiza and Mallawy), in Egypt during summer of 2004. The resulting top crosses from crossing twenty inbred lines with two line testers (Gm. 1021 and Gm. 1002) and two checks (S.C. 155 and S.C. 3080) were evaluated in summer season of 2005.Mean squares due to locations were significant for all studied traits  except, ear height and number of kernels/row. Variances due to crosses and their partitioning (lines, testers and line x testers) were significant for most studied traits. Additive and non-additive gene action played an important role in the inheritance of all the studied traits, while, non-additive gene action was more influenced  by locations than additive gene  action for most studied traits. The inbred lines Gm.( 359, 362, 364, 367, 368) exhibited highly significant and desirable GCA effects for most studied characters and grain yield, while, the inbred line Gm. 370 gave significant and desirable GCA effects towards earliness and dwarfness. The highest mean performance of crosses for grain yield were obtained from the cross Gm. 363 x Gm. 1021 (36.10 ard./fed.) and the cross Gm. 364 x Gm. 1021 (33.10 ard./fed.) relative to inbred line Gm. 1021 as tester, while, the cross Gm. 364 x Gm. 1002 (32.6 ard./fed.) and the cross Gm.365 x Gm.1002(32.7 ard./fed.) relative to inbred line Gm.1002 as tester. These top crosses outyielded and earlier than the two commercial hybrids S.C.155 ( 27.9 ard./fed.) and S.C. 3080 (29.4 ard./fed.). Moreover, twenty top crosses gave higher values from the commercial hybrid S.C.155, while, seventeen top crosses gave higher values from the commercial hybrid S.C. 3080 relative to grain yield trait. The relative increasing percentage of grain yield (ard./fed.) for the top crosses inbred line Gm.1021 as tester ,  ranged from  – 18.28%  to  29.39%   and  form  – 22.45% to 22.79% relative to S.C.155 and S.C.3080, respectively. The highest percentage values of the relative increasing for the top crosses with inbred line Gm.1021as tester were obtained form the crosses (Gm. 352 x 1021) , (Gm. 363 x 1021) and (Gm. 364 x 1021). The relative increasing percentage of grain yield for the top crosses with inbred line Gm.1002 as tester, ranged form – 22.22% to 17.2% and form – 25.85% to 11.22% relative to S.C. 155 and S.C. 3080, respectively. The highest percentage values of the relative increasing for the top crosses with inbred line Gm.1002 as tester were obtained form the crosses(Gm. 364 x 1002) and (Gm. 365 x 1002) . These crosses could be involved in maize breeding program to improve early maturity, disease resistance and higher grain yield.