This investigation aimed to study; (1)The mean performance of ten parents and their F1 diallel crosses, involving some Egyptian and exotic wheat germplasm for yield and its components. (2)The potentiality of heterosis expression, (3) General and specific combining ability and their interactions under two nitrogen fertilization levels. The analytical methods were based largely on Griffing (1956) diallel cross analysis designated as method 2 model 1. The wheat genotypes P₁, P₂, P₄, P₅, P₇, P₈, P₉ and P₁₀ as well as their F1 crosses (P₁ × P₄), (P₁ × P₅), (P₁ × P₁₀), (P₄ × P₇) (P₄ × P₉), (P₄ × P₁₀), (P₅ × P₈), (P₇ × P₁₀), (P₈ × P₉), (P₈× P₁₀) and (P₉ × P₁₀) were superior for yield contributing characters under different cases. Significant heterobeltiosis was observed in the wheat cross (P₂ × P₃) and highly significant for number of spikes / plant, (P₃ × P₄), (P₃ × P₈), (P₄ × P₅), (P₄ × P₇), (P₄ × P₈), (P₄ × P₁₀), (P₅ × P₇), (P₆ × P₇) and (P₈ × P₁₀) for number of kernels / spike; ( P₃ × P₄) for 100- kernel weight and the crosses (P₃×  P₈), (P₆×  P₈), (P₆×  P₁₀), (P₇×  P₉), (P₇×  P₁₀) , (P₈×  P₉) and (P₈×  P₁₀) for grain yield / plant under low nitrogen level. While, the two wheat crosses (P₃× P8) and (P₈× P9) showed highly significant heterosis under the combined. Sids 1 was the best general combiner for number of spikes / plant under both environments and their combined data; P₁, P₄, P₉ and P₁₀ for number of kernels / spike. In addition, P₁₀ was the promising one for 100- kernel weight, number of kernels /spike and grain yield / plant. The crosses (P₆×P₇)and(P₉×P₁₀)showed significant and highly significant SCA for number of spikes / plant; ( P₂ × P₃), ( P₃ × P₇), ( P₃ × P₈) ( P4 × P₅), ( P₄ × P₇),( P₅ × P₇) , ( P₅ × P₉) , ( P₅ × P₁₀) , ( P₆ × P₇) , (P₆ × P₈ ) and( P₈ × P₁₀) for number of kernels / spike and ( P₁ × P₄) , ( P₇ × P₉) and (P₇ × P₁₀ ) for grain yield / plant under the two nitrogen levels and their combined data .