Grain yield and its components and some growth attributes were studied at Sakha Agriculture Research Station during the three successive seasons 2008/09, 2009/10 and 2010/11, to determine the type of gene effects by using the six populations (P₁, P₂ , F₁ , F₂, BC ₁ and BC₂) of five barley crosses, namely: cross 1 (Giza 121 × Line 1); cross 2 (Giza 121 × Line 2); cross 3 (Giza 126 × Line 1), cross 4 (Giza 126 × Line 1)  and cross 5 (Line 1× Line 2). Generation means were significantly different for all studied traits in all crosses; the mean for F₁ values exceeded the mid parent for all studied traits in the five crosses for days to heading and days to maturity, were earlier than the mid-parent, indicating partial dominance. The F₂ values were approximately equal to the mid parent values and less than the F₁ mean values, indicating that inbreeding depression has occurred. BC₁ and BC₂ mean values varied according to the trait itself, it was in the direction of their respective recurrent parents for the studied characters with some exceptions. Results, in general indicated presence of non-allelic interaction for all studied traits in all crosses under study; the additive effect was more important and greater than the dominance effect for most traits. Among the epistatic components, dominance × dominance was greater in the magnitudes than additive × additive and additive × dominance in the most studied traits. Positive heterotic effects relative to the mid-parent were found for most of the traits in the five crosses, except for heading and maturity dates that showed negative heterotic effects. Also positive heterotic effects relative to the better parent were found for the most of crosses.  Heritability estimates in narrow sense were low to moderate for the studied characters in all crosses, ranged from 16.37% for spike length in the fifth cross to 66%for days to heading in the second cross. The predicted genetic advance was low to moderate in all studied traits. The crosses Giza 121 × line 1, Giza 126 × line 1 and line 1 × line 2 would be of interest in a breeding program, for improving characters of earliness, yield and its components.