The present study was carried out during the two successive seasons 2013/2014, and 2014/2015. The first season was at Kafr El Hammam Agricultural Research station while the second season was at New valley Agricultural Research station. The aim of this investigation was to estimate combining ability variances and effects of twelve genotypes which were crossed to three local wheat cultivars, i.e. Sids12, Gemmiza 9 and Sakha 93 as testers using line x tester analysis for grain yield and its components. Highly significant differences were found among genotypes, parents and crosses for all studied characters, except for No. of kernels/ spike under 50 kg N level, indicating wide genetic variability among studied genotypes. Results showed that mean squares due to both general (GCA) and specific (SCA) combining ability were significant for most of studied characters, indicating the importance of both additive and non additive gene effects in the inheritance of these traits. The GCA/ SCA ratio did not exceed the unity for most studied traits, except for 100 kernels weight and spike length, indicating that the non- additive gene effects were larger than those of the additive ones and played the major role in the inheritance of all studied characters Also, the maximum contribution to total variance of grain yield/ plant and other traits was made by the lines. The parental lines number 1,2 and 10 and the testers Sids12 and Gimmeza 9 proved to be better general combiners for grain yield per plant and most of its components which might be selected as parental materials for wheat breeding programmes under low N levels However, the hybrids (L1x T3), (L2xT1) ,(L3xT3) ,(L5x T2), (L6 xT2), ( L7 XT1), (L4 XT1), (L8xT3), (L9 xT2), (L10 XT2) and (L11 XT1), were observed as good specific combiners for grain yield per plant and some other traits, while (L4xT1) and (L10x T2) can be recommended as good genetic materials for wheat breeding programmers under low N Level. Hence, they would result in transgressive segregants for grain yield per plant in late segregating generations due to the predominance of non- additive gene action.