Field experiments were carried out  during the three successive  growing seasons of 2015/2016,   2016/2017  and  2017/2018 in the Agricultural Research station at South Valley Research Station in Toshka Region. Inheritance of plant height, grain yield and its components was studied in three barley crosses, i.e., (I) Giza 126 x C.C.89, (II) Line1 x Giza 124 and Giza 124 x Giza 126.  The six populations, i.e.; P₁, P₂, F₁, F₂, BC₁ and BC₂ for each of the three crosses were evaluated. The additive and dominance genetic estimates, as the type of gene effect, were significant for most studied traits in the three crosses. Also, significant estimates for one or more epistatic gene interactions were displayed   for all studied traits in the three crosses except, 1000-kernel weight in the second cross, no. of spikes and grain yield per plant in the third cross. Highly significant positive heterosis over the mid-parent values were obtained for plant height and no. of kernels per spike in the three crosses, no. of spikes per plant; spike length and grain yield per plant in the first and second crosses. Highly significant positive heterosis over the better parent was obtained for plant height in the second and third crosses, grain yield per plant in the first cross and spike length in the second cross. Highly significant positive values for inbreeding depression were detected for plant height and spike length in the three crosses, no. of spikes per plant and grain yield in the first and second crosses and for no. of kernels per spike in the first and third crosses. High heritability values, in broad sense were obtained for plant height and 1000 -kernel weight.  Moderate values were obtained for no. of spikes per plant, spike length and grain yield/plant. On the other hand, low to moderate heritability values in narrow sense were detected for all traits studied. Low to moderate values  were obtained from the predicated genetic gain for all the studied traits in the three crosses. It could be concluded that, the best crosses showing advanced values of the mid-parent heterosis and predicted genetic advance from selection for grain yield and some of its components in this study were crosses 1and 2 .so, it can be used these crosses in breeding program to improve the barley crop.